Mario & Sonic at the London 2012 Olympic Games (Nintendo 3DS)

Mario & Sonic at the London 2012 Olympic Games is a sports title for the Nintendo 3DS with a Wii version of the game released as well. Both games make up the third installment of the Mario & Sonic series, which take place in London, home of the.

Characters
In the 3DS version of the game, there are a total of 20 playable characters (the character roster being identical to the one featured in the Nintendo DS version of Mario & Sonic at the Olympic Winter Games). However, only certain characters can play certain events. These characters are identified in five different classes and get their own storyline. Some characters can compete in other events that they would not normally be playable in Story Mode.

Rivals

 * Dry Bones - Sailing - 470 (Pair)
 * Dry Bowser - Sailing - 470 (Pair)
 * King Boo - Badminton (Doubles)
 * Boo - Badminton (Doubles)
 * Magikoopa - BMX
 * Eggman Nega - 4x100m Relay
 * Omega - Wrestling - Freestyle
 * Jet - 3000m Steeplechase
 * Rouge - 100m Backstroke

Referees

 * Toad
 * Cream
 * Lakitu
 * Shy Guy
 * Charmy
 * Espio
 * Omochao

Other

 * Koopa Troopa
 * Shy Guy
 * Goomba
 * Thwomp
 * Toads
 * Egg Pawn
 * Flapper
 * Orbot
 * Cubot
 * Chao

Opening
Bowser and Dr. Eggman watch over London from the inside of Elizabeth Tower, but the doctor tells Bowser they're already starting the 2012 Olympics and they haven't got their invitations yet. They believe the other athletes were intimidated and tried to keep them excluded. Bowser suggests that he could use his new machine. Dr. Eggman agrees and puts a mysterious pot in side of it and presses the start button. Then, colorful fog covers all over London.

As the referees are prepping everything, a colored fog rolls in. Toad and Omochao end up separated. Toad runs into and is attacked by what appears to be Mario and Sonic while Bowser and Dr. Eggman laugh in victory.

Heroes Story, Part 1
The night before the games, Sonic and Tails are exploring London when a strange red fog rolls in. While in the fog, they are confronted by foggy impostors of Mario and Luigi, who try to impede them from investigating by challenging them to an event. Sonic and Tails win and the clones disappear. They later follow Boo and meet King Boo, who challenges them to a Badminton-Doubles event. They defeat them in the event and King Boo and Boo escape while Sonic destroys the machine. Sonic and Tails go off to rest for the night.

The next day, Mario and Luigi find Toad, who is apprehensive towards Mario after what he went through with the foggy impostors at the Stadium and find out that the fog is colored blue. They then encounter clones of Sonic and Tails. The latter challenges the former to an event and disappear after their loss. The Mario Bros. rush through the fog. Toad and Omochao find Dry Bowser and Dry Bones and mistake them for the brothers. Fortunately the duo arrive to be challenged to a Sailing 470: Pair event. They then defeat them and the skeletal villains escape the Stadium while the winners destroy the fog machine. Noticing fog in Hyde Park, Toad and bros go to find Princess Peach.

Girls Story
At Hyde Park, Daisy and Amy are wandering around and find the impostors of Peach and Blaze. They are challenged to an event where they defeat them. More impostors come and knockout the confused Daisy and Amy.

Later on, Peach and Blaze defeat the impostors that attacked Amy and Daisy and save them. When a purple Toad recalls seeing a white bat in an area nearby, they find the figure to be Rouge. In a strange manner, Rouge challenges Peach to a 100m Backstroke event where the princess defeats her. After her loss, Rouge comes to her senses and has no recollection of what happened. Rouge leads the girls out to the fog machine. Afterwards, Toad, Mario, and Luigi arrive to see they are okay. Rouge recalls breathing in the fog and that someone told her to trap them in it. She recalls it was at the British Museum and the being was Eggman. The five females stay behind while Mario and Luigi go with Toad to the museum.

Challengers Story
After last night, Sonic and Tails discover more fog at the London Bridge. They encounter Yoshi and try to help him out. Then, Shadow and Silver impostors appear. Agitated by their behavior, Yoshi challenges them to an event. After Yoshi defeats them, they disappear and the real Shadow and Silver appear. Then, somebody comes speeding past with the three hedgehogs in pursuit. The speedster turns out to be Jet the Hawk. After rudely declining to help them and attempting to take the hidden machine, Shadow challenges him to a 3,000m Steeplechase match. After being defeated, Jet promises to help out when they discover the machine. He tries to break it until they hear Bowser's voice. Bowser Jr. reveals himself next to the machine and that he was the one doing his father's voice by taking a breath of the fog. After he's downgraded for habit of living in his father's shadow, Junior challenges the other three Challengers to an event, promising to tell them where Bowser is when they win. After he's beaten and Shadow destroys the machine, Bowser Jr. breaks his word and leaves after slipping out Bowser and Eggman's alliance. While Yoshi chases him down, Shadow suggests they split up to comb different areas; with Sonic and Tails taking the British Museum.

Heroes Story, Part 2
At the British Museum, Mario, Luigi, Toad, Sonic, and Tails meet up. The heroes then find returning impostors of themselves and beat them in an event. After more searching, they discover Dr. Eggman Nega after Toad bumps into him and challenge him and his Shy Guys to a 4x100m Relay where he is defeated. He then disappears while Mario and Sonic destroy the machine he was guarding. They then search the museum for sources about the fog where they discover that it's called the Phantasmal Fog and was stolen by the legendary pirate, William Kidd 300 years ago. Espio the Chameleon appears and tells them Bowser and Eggman are still causing trouble at different venues. Charmy Bee directs them all in different directions. Sonic goes solo while the other heroes pair up with the referees.

Wild Ones Story
At the Wrestling Stadium, Donkey Kong has finished a workout and was about to enjoy a banana, when Espio and Tails meet him to warn about the rampage of E-123 Omega. The robot arrives and crashes into him. Shaking this off, Donkey Kong is uninterested in Omega's challenge at first, but reconsiders when he realizes Omega had ruined his banana. They do a Wrestling-Freestyle Match where DK wins. Tails discovers that Eggman had put a chip in him that caused him to go rampant. Omega reactivates and forgets everything that happened, but apologizes to DK. He promises to help out and he goes with Espio and Tails.

Later on, Sonic arrives at the Volleyball court and narrowly dodges an ambush by Bowser. Knuckles and Vector arrive and explain Amy asked them to check out the area. They challenges the Koopa King to an event. They defeat and corner him and Knuckles crushes his machine. Sonic moves on while his powerhouse friends interrogate Bowser.

Tricksters Story
At the Tennis Court, Waluigi is looking for a spot to spy on Luigi and learn his weaknesses until Metal Sonic comes along and breaks his telescope. Angered, Waluigi accepts a challenge from Metal Sonic and defeats him. The robot runs away and Waluigi follows him; oblivious to his witnesses, Luigi and Charmy.

Meanwhile, Wario is planning to make an Un-Discount Snack Emporium, but a fog machine is in the way. He then tries to disable it, only to be confronted by Dr. Eggman. The rounded men do a match which Wario wins. Dr. Eggman, unfazed, lets Wario try to destroy his machine. Wario prepares to only realizes he made himself dizzy because the machine was only a hologram. Eggman escapes while a vexed Wario recovers and follows after him into the fog with Mario and Toad behind him.

Waluigi and Wario meet up and confront the scientist and his creation while Mario, Luigi, Toad, and Charmy sneak up on them and see what they are doing. Dr. Eggman and Metal Sonic challenge Wario and Waluigi to a match where Wario and Waluigi win. Wario destroys the real and final machine as Eggman and Metal Sonic collapse in defeat. Mario, Luigi, Toad, and Charmy congratulate them as they move on while the Wario and Waluigi volunteer to keep an eye on the villains, intending to resolve their unfinished business.

Clear Skies Again
The heroes get together again at the main stadium, and tell each other that all the fog machines were destroyed, with help from members of the Tricksters and Wild Ones. Everyone rejoices because the opening ceremony can continue.

Back at the wrestling stadium, Knuckles backs Bowser into a corner and punches him, only to reveal it is a fake, much to his and Vector's confusion. The same situation happens when Wario and Waluigi corner Dr. Eggman, who suddenly disappears as well, much to their dismay.

In Big Ben, Dr. Eggman and Bowser are happy that they have everyone fooled. The doctor then goes to his machine and resolves to cover London in fog again, but with ten times the strength. Bowser agrees with this plan. After pressing the button, fog spreads very quickly throughout the room. The top of the machine breaks and more fog spews out rapidly. It surrounds Bowser and Dr. Eggman, who feel power welling up within them. The two evil doers laugh as lots of rainbow fog spews from the Big Ben.

Heroes Story, Part 3
After the united heroes save Cream the Rabbit from more of their foggy clones, Omega recalls something at Stonehenge. At Stonehenge, they and Toad hear Magikoopa's voice as he challenges Sonic to a BMX match. The blue hedgehog defeats him causing the sneaky wizard to run away after flinging Omega into Big the Cat. Omega recalls that when he was corrupted, he was asked to transport the urn containing the fog to Eggman's lair at Big Ben. After finding the seal, they head over there. After defeating more clones, the heroes advance to the lair while Omega and a weakened Toad head back to the stadium.

At the Factory, Mario, Luigi, Sonic, and Tails arrive to defeat Bowser and Eggman only to find they are greatly powered by the Phantasmal Fog dwelling in them. Toad then uses the radio communicator to talk to Tails and tells him that everywhere else is cleared up thanks to the other athletes, opponents, and referees and the Olympic Games are up to them. The quartet face the powered-up Bowser and Eggman and defeat them. While Luigi and Tails hold the villains off, Mario and Sonic destroy the machine and seal the fog in the urn. Disappointed, Bowser and Eggman complain how they will never be in the Olympics. Toad says that their names are on the competitor list. While wondering why they have not gotten their invitations yet, Toad explains they can bring their ID. The two villains are exasperated at this misunderstanding and realize they do not have their ID's but Tails says Mario and Sonic can vouch for the sheepish pair.

At the Opening Ceremony, Bowser and Eggman are at the front watching Mario and Sonic present the Olympic Games.

Challengers Bonus
Bowser Jr. arrives in England to compete in the games. Unfortunately, he took a wrong turn and ended up in Stonehenge instead of London. After being informed by Shy Guys, he sees Yoshi training for the games and challenges him to an Olympic event. Junior wins and calls on his Bullet Bill to bring him to London.

Later, Omochao and a regular Chao are being threatened by two of Dr. Eggman's robots for unknown reasons. Shadow and Silver arrive to defeat them, but Junior, flying overhead, accidentally falls off of his Bullet Bill and destroys both robots by landing on them. The two Chao are grateful and the two hedgehogs are impressed. Wanting to see how strong he really is, they challenge Jr. to a 2-on-1 Olympic event, which Jr. wins. Shadow and Silver are good sports and congratulate the young Koopa. A nearby Goomba convinces Jr. to look for more robots so that he'll be even stronger.

Arriving at the stadium, Junior and the Goomba see Dr. Eggman measuring Metal Sonic's time running around the track. Junior challenges Metal Sonic to an event. Thinking this would be perfect practice for the robot, Eggman agrees, on the condition that Junior becomes in debt if he loses. Junior accepts, telling Eggman that if he wins, he has to tell his father of his victory. With that, the child and robot set off. Jr. eventually wins. Eggman tries to examine Junior to see what he needs to do to upgrade Metal Sonic, but Junior angrily stops him, demanding a drink and snack in exchange for Eggman trying to con him. The scientist reluctantly agrees.

Wild Ones Bonus
Bowser angrily stomps through London, followed by Goomba, Lakitu, and Magikoopa. His minions state wrong facts to him. Magikoopa, believing he's still upset over what happened in Vancouver, offers to use his magic to keep Mario and his friends out of the games, but this just agitates Bowser further. The minions decide to cheer him up by secretly letting him win some Olympic events against the other Wild Ones the next day. Their first target is Donkey Kong. Magikoopa promises a pile of bananas in exchange for taking Bowser on in an event, but when the ape agrees, the wizard summons a Thwomp to fall on DK, making him dizzy and less likely to win. Bowser arrives and wins against DK. Behind his back, however, Magikoopa makes it up to DK by getting him the bananas that were promised.

Later, the Magikoopa, as well as the Lakitu and a Dry Bones, somehow convince Knuckles and Vector to rendezvous. To convince them to fight, the Magikoopa uses his magic to make the Lakitu and Dry Bones to look like Charmy and Espio, respectively. The powerhouse duo notice the two fake members acting funny, but agree to fight Bowser. The Magikoopa then summons giant versions of a Chain Chomp and Piranha Plant to bite Knuckles and Vector, respectively. Similar to DK, this makes the two dazed and less likely to win. After Bowser defeats them, the Goomba (who had led Bowser to the arena) quickly escorts him out before Knuckles and Vector, held back back by the still disguised Lakitu and Dry Bones, ask too many questions.

For Bowser's last false victory, the minions plan to place him in a tennis game with his archenemy Mario. Unfortunately, Boo failed to trick Mario into coming to the court because Mario was much more circumspect than DK, Knuckles, and Vector and recognized the scam. After the other minions come, Dry Bones distracts Bowser while the other minions think of a back-up plan. The Magikoopa decides he'll have to transform one of them into Mario. Dry Bones can't do it because he is talking to Bowser and only speaks in "clacks", neither Boo (who Goomba suggests for failing to trick Mario) or Lakitu can do it because they float, and they can't bring in a Shy Guy. Goomba is terrified to pretend to be Mario, but agrees when Bowser's patience is wearing thin. Bowser challenges "Mario" to a game of tennis and wins. After the match, Bowser Jr. arrives and is happy that his father won and says he wants to be just like him, while the minions celebrate over the success of their plan. Bowser notices that his minions are finally satisfied that he is back to his old self, as it turned out he had a toothache.

Tricksters Bonus
In his secret headquarters inside Big Ben, Eggman defeats Metal Sonic in a match of Taekwondo. He is unsure of what to do to upgrade his creation. His other robot minions, Orbot and Cubot, see Waluigi on the monitors and suggest him for practice. They confront Waluigi and convince him to battle, saying it would make good practice for defeating Luigi in the Olympics. Metal Sonic wins with Eggman deducing that Metal Sonic possesses speed, but not strength.

The robots come across Wario and ask him to challenge Metal Sonic so that the robot may go against Wario's strength while guaranteeing an edge on Mario. However, unlike Waluigi, defeating his rival isn't good enough for Wario, so he and Eggman settle on a bet: if Wario wins, Orbot and Cubot come work for him; if Metal Sonic wins, Wario has to give Eggman something of his. Metal Sonic emerges victorious, so Wario gives Eggman an old urn he got from an antique shop, claiming that it is magic. Eggman seems to recognize it and accepts it.

Back in his headquarters, Eggman places the urn inside a machine. The machine slightly unseals the lid on the urn and gray fog pours into the room. Some of this fog takes the shape of Sonic and Eggman challenges it to an event. Eggman appears victorious and the Sonic impostor vanishes into thin air. Eggman explains to his minions that this urn contains the legendary Phantasmal Fog, stolen 300 years ago by the legendary pirate William Kidd. The urn eventually ended up in the British Museum, where it was recently stolen. He says the fog shapes into whoever the person in it is thinking about, explaining the impostors in the main story. Eggman resolves to completely unseal the urn after he and Metal Sonic are done training for the Olympics.

Girls Bonus
At Hyde Park Peach, Amy, Blaze, and three Toads are setting up the invitations for all of the athletes, however Amy suggests she take Sonic's invitation to him personally but the others don't want Amy to go and insist that she stay and help the others work. However, after more begging, Blaze suggests that if Amy can beat her in a competition she will let her go. Then, after Amy beats her, Blaze accidentally scatters the invitations. Amy then decides to stay.

Later, Daisy shows up and talks about going shopping. Amy wants to go with her. Peach challenges Daisy and says if she wins, Daisy must stay and help. If Daisy wins, Amy can go with her. After Peach wins, they all go out for a break. But when they return, the wind had knocked off all of the invitations to the ground. After they pick them all up they realize that they are missing Bowser's and Eggman's invitations, so they make new, detailed better ones.

Later, Peach and Amy meet Bowser and Eggman in the park and end up playing a round of Beach Volleyball to calm them down. After they win, they go fetch their invitations, but at the same moment the blue and yellow Toads go to deliver them and they drop Eggman and Bowser's next to them after the two villains startle them. Bowser and Eggman look at how well the invitations are written and think that Peach and Amy were writing love letters to Mario and Sonic. Confiscating them, Bowser and Eggman, believing the pink girls instantly forgot their invitations. go off together looking around London before they do something evil. The girls assume that the villainous duo took their invitations themselves, so they all decide to go out shopping together before the Olympic Games start.

The last part states after sightseeing, Bowser and Eggman forget about the invites. The fourth wall is broken when it says that the player is the only one who fully understands the misunderstanding that led Bowser and Doctor Eggman to fog up London and sabotage the games.

Olympic Mode
There are two ways to play the Olympic Mode. Each mode allows up to 4 players.

Highlight Match
This is more like the Single Match mode in the Wii version of the game. 4 players compete or co-operate in an event that is selected by the host. After selecting an event and the difficulty of the computers (COM Level), each player chooses 1 character to use from one predetermined category of the 5 total (Heroes, Girls, Wild Ones, Tricksters & Challengers).

The players play the event according to its rules. After an event, a medal is given to the player as long as the player doesn't get 4th place. If two or more players/teams tie for a position, the same medals are given, unlike the other handheld titles. After an event, the player can choose to play the same event, change the event or quit the game (this is shown as Disconnect in case of multiplayer).

When playing in Free-for-All events that require players to split into pairs
The seeding is determined randomly, and one player plays against the other player in their pair. After the semifinals have ended, the winners play against each other for 1st and 2nd place and the losers play against each other for 3rd and 4th place.

Note that the players will not see who will duel up against until the semifinals have started.

In Case of Team Events
To ensure that there are always 4 teams in an event, extra COM-controlled teams are added based off how many players are on a team.
 * With 2 members per team - There are 2 extra COM-controlled teams. The first COM-controlled team are a team of Koopas while the second COM-controlled team are a team of Chao.
 * The extra COM-controlled teams do not appear in any event.
 * In case of tournament-based matches, the extra COM-controlled teams will always lose the semifinals.
 * In the case of Sailing - 470 (Pair), the extra COM-controlled teams will always place 3rd and 4th.
 * With 4 members per team - All 4 characters from that group compete against the 3 COM-controlled teams that are all Shy Guys of a specific color relating to their team number.
 * The COM-controlled teams of Shy Guy only appear in the 4 x 100m Relay event.

Medley Match
In Medley Match mode, the player can compete in medleys made up of several different Olympic events to earn points, aiming to score more points than their opponents. For each event, the player will receive a number of points based on their placement in it, winning 10 points for first place, 6 points for second place, 4 points for third place and 2 points for fourth place.

In this mode, certain events are always treated as bonus events, giving them slightly different rules and awarding different point scores at the end of the event, mainly based on the score that the player achieved. The following events are treated as bonus events:
 * Marathon- Only a single round of the event is played, with the score being determined by the water bottle that the player grabs. The characters are ordered in the reverse order of their current overall placement, such that fourth place is in the lead while first place is at the back. Collecting the rainbow colored water bottle scores the player 15 points, the blue water bottle scores 10 points, the white water bottles score 5 points each and failing to collect any of the water bottles awards the player 0 points.
 * Basketball- The player will have a short practice session with a cursor before being able to make a single shot without the cursor to determine their point score for the event. The color of ball that the player receives depends on their placement in the medley, with higher ranked players receiving worse balls than the higher ranked ones. White and orange balls are worth 5 points, blue balls are worth 10 points and rainbow colored balls are worth 15 points.
 * Handball- The event is played as normal with ten shots thrown by the Egg Pawns, and the type of balls thrown depending on the player's placement, with lower-ranked players receiving more multiple point scoring balls than those in higher positions.
 * Football- The event is played mostly as normal with only five shots thrown by the Shy Guys, and different types of balls thrown depending on the players' placement, with players in low positions receiving more multiple point scoring balls than those in high positions.
 * Keirin- The characters start the event with advantages based on their placement, with the fourth placed character starting further ahead than the third place character and so on. The event plays as normal, but scores are awarded so that first places gets 15 points, second place gets 10 points, third place gets 5 points and fourth place does not receive any.

Upon creating a new file, the player completes the Warm-Up Medley consisting of three events, 100m, 100m Freestyle and Judo. Any records set during this medley do not count, and the player cannot see the results of the events. This medley is not available in the game afterwards.

There are two ways to play Medley Match, standard mode and quick mode. Standard allows players to choose a character from each of the groups, as well as allowing them to set and select a group of favourite characters. When playing two-person medleys, the second character will be randomly picked, and when playing team medleys the player's selected character will be the lead character. Each event shows the player the instructions screen before playing, and also provides intermittent screens between events showing each player's current position, point increases and position changes and often features commentary from Toad, Wenlock and a Chao about recent occurrences. In the quick mode, all of these things are absent, with the player receiving a random selection of characters and their current position in the medley and number of points being displayed in the bottom right of the Touch Screen during the events. The quick mode is the only mode in the game where the main instructions screen of an event can be fully skipped.

London Games
London Games mainly consists of medleys based on a selection of events from a specific class, but also features some medleys that are a combination of classes or based on the team size instead. Cells with yellow backgrounds indicate bonus events.

Variety
Variety Medleys are made up of events that are grouped together based on things like the type of gameplay or input used in the events. Cells with yellow backgrounds indicate bonus events.

Party Mix
Party Mix medleys function differently to other medley types, as while there are three different individual medleys, all of them use a randomised selection of single character events. All three Party Mix medleys are available at the start of the game, with the only differences being the number of events in each and the amount of points awarded for the Party Mix Awards event. The main difference to Party Mix medleys is the addition of Party News events, which are various randomly occurring events in the form of a news broadcast hosted by Omochao that appear at various times in the medley and often award players bonus points. The Party News events that can occur are:
 * Event Selection: A randomly selected human player chooses between four event types, including Timing games, Microphone games, Judgment games, Finesse games, Rhythm games, Flexibility games, Do-or-Die games, Wrist workout games, Repetition games, Balance games and Intelligence games. An event is selected from the player’s chosen category and played as the next event. During this Party News event, a picture is taken of the player choosing the event and is used to announce the chosen Olympic event.
 * Captain Drake’s lost treasure: The lost treasure of is found, and players take it in turn to select a random chest that includes a number of bonus points. The number of points varies between players to even the scores such that players in lower positions will receive more points than those in higher positions, and the other players will be able to see how many points are in the choosing player's chests.
 * Bonus Update!: Announces all of the player’s current ranks and the upcoming bonus events before they are played.
 * Party Mix Awards!: Handed out at the end of each medley, awarding players points for the most and least points earned in a certain event class, 10 and 15 points respectively for Party Mix 10 Medley in one class, 15 and 20 for Party Mix 15 Medley in two classes and 20 and 25 for Party Mix 20 Medley in two classes. This Party News event also makes use of the camera when revealing players that won awards and before announcing the final results, with computers receiving one of a number of images to represent them.

Custom
Custom Medleys consist of medleys that the player has made using the Make an Event Medley mode or traded with another player using the Trade an Event Medley function. The player can create up to twenty medleys, with the options of making medleys with five single character events or three two or four-character team events. The player can store up to twenty medleys across all types, and is also able to name their medley. Custom medleys have a rarity rating, which is rated from 1 to 10 stars, which is based on both the average of each event's Best Event Ranking from 1 to 57, and a "hidden value" that takes the ratio of the average score of the events in the medley to the average score of all 57 events in the game. An event's Best Event Ranking is determined by three attributes: The three attributes determines a score for the event used to determine the Best Event ranking, which is shown to the player while making their medley. By picking events with a lower number ranking (the lower this number, the better the player is at an event), the rarity rating for the event will increase. The ranking does not take into account events being in other classes though, meaning that if a player's top events are distributed over single character, double character and quadruple character events, the maximum rarity rating of ten cannot be obtained unless the player changes their top ranked events by repeatedly playing and winning the events in either Highlight Match, Medley Match or Story Mode. A "hidden value" is also another factor of determining the rarity rating, which is the ratio of the average score of the events in the medley to the average score of all 57 events in the game. When a player plays an event, this "hidden value" will increase very rapidly for medleys containing the event, and decrease very slowly for medleys not containing the event. This "hidden value" will have an effect on the rarity rating given to a medley containing certain events.
 * Frequency: Determined by how many times the player has played the event. In the Play Data section of the Record Log, the player can check which 5 events the player has played the most.
 * Difficulty: The average level of COM opponents that the player competes against in the event. This attribute will change even if the player cannot compete against a COM player or team because of the number of players or the selected event.
 * Performance: The average finishing position of the player in the event.

When playing multiplayer, the medleys available in the Custom list are based off medleys in the host's list, and only the host can win badges for winning a medley with a certain rarity rating. The rarity of the medley does not change once a medley is created and the player must recreate the medley to determine if the rarity rating has changed. The COM Level that the player competes against in a custom medley does not affect whether a badge will be won for winning a custom medley with a specific rarity rating.

Multiplayer
Local Play and Download Play are both offered for 2 to 4 players. In Local Play, the player can play a single "Highlight Match" with other players or a "Medley Match". Records set during local play (including events that are co-op events) are saved.

Unlike previous Mario & Sonic games on DS, there are some limitations to Download Play. In Download Play, the player can play any event in a Highlight Match with character selection, or a limited version of Medley Match called "Party Mix Demo DL Medley" where everyone plays as colored Yoshis, regardless of the events chosen. In addition, the announcer and the characters don't talk on systems that are playing via Download Play. Some features are also disabled and also, the Top Screen is fully white when selecting an event or a character. Furthermore, players using Download Play cannot save their data, and when playing Download Play, there is different music for certain areas of the game.

Other Differences in Multiplayer Matches
Different things can happen depending on the selected event and the amount of players that are participating.
 * When playing in multiplayer, each player may team up for an event depending on which event is selected.
 * The controls in an event may be different in co-op than in single player.
 * When only 2 players are connected, the human players automatically go to the Finals in case of tournament-based events.
 * When selecting an event or medley with 2 members per team, the following will happen depending on the number of players connected:
 * 2 Player - The players will always pair up against the COM.
 * 3 Player / 4 Player - Each player selects a character. After that, the host selects the team that each player will be on. If there are 3 players, the character that is not selected by either of the players will join the team of the single player.
 * When selecting an event or medley with 4 members per team, the following will happen depending on the number of players connected and if the the COM can control some characters of the user-controlled team:
 * If there are 4 players, each player selects a character. The order of the characters is P1 > P2 > P3 > P4.
 * If there are less than 4 players and the COM can control some characters of the user-controlled team, each player selects one character. The COM will control the characters that were not selected by the other players in certain events. This also applies in Single Player mode.
 * If there are less than 4 players and the COM cannot control some characters of the user-controlled team:
 * 1 Player - The player will not select a character. Instead, the order of the characters in the Select Character screen will be the order of characters in the event.
 * 2 Player - Both players each select 2 characters. P1 will control the first and third characters while P2 controls the the second and fourth characters.
 * 3 Player - P2 and P3 both select a character, with P1 selecting 2 characters. P1 will control the first and fourth characters, P2 controls the second and P3 controls the third.

Events
There are 57 events in the game, split into 11 sports. The selected event determines which character group will be used:
 * Athletics
 * 100m / Heroes
 * 110m Hurdles / Challengers
 * 1500m / Challengers
 * 3000m Steeplechase / Challengers
 * 4x100m Relay / Heroes
 * Marathon / Heroes
 * Long Jump / Tricksters
 * Triple Jump / Challengers
 * Hammer Throw / Wild Ones
 * Shot Put / Challengers
 * Javelin Throw / Wild Ones
 * Pole Vault / Heroes
 * 20km Race Walk / Heroes


 * Aquatics
 * 100m Freestyle / Heroes
 * 100m Backstroke / Girls
 * 100m Breaststroke / Tricksters
 * Water Polo / Challengers
 * Platform Diving (Synchronised) / Tricksters
 * Synchronised Swimming (Duet) / Heroes
 * Synchronised Swimming (Team) / Girls
 * 10km Marathon Swim / Challengers


 * Court & Field Sports
 * Badminton (Singles) / Tricksters
 * Badminton (Doubles) / Heroes
 * Table Tennis (Doubles) / Heroes
 * Basketball / Challengers
 * Beach Volleyball / Girls
 * Tennis (Singles) / Wild Ones
 * Hockey / Tricksters
 * Handball / Tricksters
 * Football / Wild Ones


 * Contact Sports
 * Judo / Heroes
 * Boxing / Wild Ones
 * Fencing - Epée / Heroes
 * Taekwondo / Tricksters
 * Wrestling - Freestyle / Wild Ones


 * Gymnastics
 * Rhythmic Ribbon (Team) / Girls
 * Balance Beam / Girls
 * Floor / Challengers
 * Rings / Wild Ones
 * Horizontal Bar / Heroes
 * Trampoline / Challengers


 * Cycling
 * Sprint / Heroes
 * Keirin / Girls
 * Omnium / Girls
 * BMX / Heroes


 * Equestrian
 * Show Jumping (Team) / Girls


 * Boat Games
 * 1000m Kayak (Singles) / Tricksters
 * Canoe Slalom (Pair) / Girls
 * Rowing - Quadruple Sculls / Heroes
 * Sailing - 470 (Pair) / Heroes


 * Shooting
 * Double Trap / Wild Ones
 * Archery (Individual) / Girls
 * Archery (Team) / Heroes
 * 25m Rapid Fire Pistol / Tricksters


 * Weightlifting
 * Weightlifting / Wild Ones


 * Multi-Discipline
 * Triathlon / Heroes
 * Modern Pentathlon / Heroes

Demo
On March 1, 2012, a demo of the 3DS version of the game was released on the Nintendo eShop. Five events are playable in the demo: 25m Rapid Fire Pistol, Football, Trampoline, 50m Backstroke and BMX. The player cannot choose his or her character or name, as that is always M&S. Each event is played using one of four characters, and each set of characters in an event belongs to a particular class. The 25m Rapid Fire Pistol uses the Tricksters class, the Football event uses the Wild Ones class, the Trampoline event uses the Challengers class, the 100m Backstroke event uses the Girls class, and the BMX event uses the Heroes class. The demo can be launched a maximum of 30 (20 in Europe) times once downloaded.

References to other games

 * Paper Mario series - The HP replenish sound is used for a Skill character's special move in Badminton and Beach Volleyball.
 * Mario & Sonic at the Olympic Winter Games - All the Mario franchise and Sonic series songs return as well as the rival themes. In story mode on the 3DS version, Toad, Magikoopa, and Silver reference the story mode of this game.

Trivia

 * This is the first Mario & Sonic game to feature the new Sonic voice actors, with the exception of Dr. Eggman, who kept his voice actor.
 * This is also the first Mario & Sonic game to feature Bowser's current voice, provided by Kenneth W. James.
 * At the beginning of the Story Mode, Bowser actually refers to himself by his last name, "Koopa."
 * The 4th place music from the Wii version of the game plays if the player places 3rd. This is because there is a different music piece for finishing 4th.
 * This is the only Nintendo 3DS title in which the in-game font is taken from Super Mario Galaxy.
 * Originally all characters were going to have swimsuits, but it was rejected by Sega because Sonic cannot have his shoes removed.