Mario & Luigi: Partners in Time

Mario & Luigi: Partners in Time (Mario & Luigi RPG 2×2 in Japan) is a turn-based action RPG video game for the Nintendo DS, developed by AlphaDream and published by Nintendo, and it is the second title in the Mario & Luigi series. The story of the game involves Mario and Luigi, time-traveling between their present and past times, and teaming up with their infant selves, Baby Mario and Baby Luigi, to stop the invasion in the past by the enemy alien species called the Shroobs. The English and Spanish names of this game are puns on the title of the short story compilation Partners in Crime.

Though the game is primarily a turn-based RPG, the game mixes in action RPG and platformer elements, which is the primary gameplay point of the Mario & Luigi series. The game takes many elements from the first game, Mario & Luigi: Superstar Saga, and revamps it to take advantage of the Nintendo DS's new features. While it makes almost no attempt to use the touch screen (Mario must rub the dirt off of a drawing at one point), the game used the addition of the and  buttons, the extra screen, and greater system resources.

Like its predecessor, it is one of the few Mario games to have been released in North America before Japan. However, the game was re-released in the Wii U Nintendo eShop in Japan first.

Story
During Mario and Luigi's infancies, Shroobs from a withering distant planet find the Mushroom Kingdom and invade it. The invasion forces Baby Mario, Baby Luigi, Baby Peach, Toadsworth the Younger, and Baby Bowser (who had been attempting to capture Baby Peach at the time) to flee in the Koopa Cruiser.

In the future, Princess Peach, Toadiko, and Toadbert travel to the past via Professor E. Gadd's time machine, which is powered by the Cobalt Star. But when the device returns, it is occupied by a hostile alien, forcing Mario and Luigi to use a newly-formed time hole in the castle gardens to go to the past and find Peach. Before they proceed to Hollijolli Village, they receive Stuffwell, a talking suitcase made by E. Gadd, to assist them and help them carry supplies on their quest. Upon their arrival in Hollijolli Village, they are attacked and defeated by a trio of Shroobs, but Baby Mario and Baby Luigi arrive and save their adult selves soon afterward. The adult Mario Bros. join the rest on the Koopa Cruiser, but the cruiser is attacked by Princess Shroob, the leader of the Shroobs, and crashes into Baby Bowser's Castle where Mario, Luigi, Baby Mario, and Baby Luigi find a Cobalt Star Shard. They travel through another time hole to the present day Princess Peach's Castle with Toadsworth and Baby Peach, who they leave behind as they return to the past through a new time hole opened by the Cobalt Shard.

The time hole leads to Toadwood Forest, where the group finds a weakened Toadiko wrapped in a tree's branches. She manages to tell them that the Shroobs have kidnapped Peach before the tree sucks away the last of her vim. Shroob UFOs then attack and fire at Toadiko and she turns into a Shroob Mushroom, which the aliens use to fuel their ships. The Mario Bros. travel to the Shroobs' Vim Factory to shut down the operation. The babies receive hammers after they defeat the Hammer Bros. and when the protagonists defeat the Swiggler, they briefly obtain a second Cobalt Shard before Baby Bowser steals both shards and Kamek picks him up and they flee.

After a brief stop in Peach's Castle of the present and learning the Toadsworth Twist, the protagonists use another time hole to travel to Yoshi's Island of the past, where all the Yoshis have disappeared. They find Kamek and follow him back to Baby Bowser; Kamek attacks them but is defeated and they chase after Baby Bowser, who swallows the Cobalt Shards when they corner him. All of them are then eaten by a massive Shroobified Yoshi monster, Yoob. Inside Yoob, they find the missing Yoshis and an amnesiac Toadbert, who is carrying a partly obscured drawing that he made of what happened during the battle between Peach and Princess Shroob. After the Mario Bros. and their baby counterparts defeat Sunnycide, an egg monster, everyone escapes Yoob, including Baby Bowser, who coughs up the Cobalt Shards later on after choking on the last remaining Yoshi Cookies.

After learning the Bros. Ball, the protagonists next visit Gritzy Desert, where they meet Kylie Koopa, and find a secret entrance to the Koopaseum, arriving in time to witness Princess Peach being swallowed whole by Petey Piranha. The brothers defeat the Shrooboid Brat in the arena, angering Princess Shroob who breaks the floor and sends them falling into Gritzy Caves. The brothers fight and defeat Petey Piranha, recovering a Cobalt Shard and saving Kylie Koopa (who had almost been fed to him too). They find Princess Peach, whose face is covered by a Shroob Mushroom, and take her back to the present day castle. Bowser attempts to kidnap her but falls through a time hole to Thwomp Volcano. After learning the Baby Spin and Baby Cakes, the brothers follow Bowser and travel to the top of the volcano. When they arrive, they find Peach's crown. After that, the volcano erupts and they flee down the right path. They meet Professor E. Gadd’s younger self, who thinks up of an idea of making a machine that could douse the volcano's fire, which the older E. Gadd creates in the present time. He then uses his quickly built invention to spray water into the time hole and stop the volcano. After a skirmish with the angry resident, Mrs. Thwomp, the Mario Bros. are carried into the volcano by her husband, Mr. Thwomp, where they solve various puzzles and fight and defeat Bowser and Baby Bowser (who had been shot into the volcano after being blown away from Yoshi's Island). Bowser is sent careening back to the present while Baby Bowser flies off on his own, but before the protagonists can collect the princess, she is sucked up by the Shroob Mother Ship. The brothers board the ship and team up with Kylie to try and save Peach, but they all simply end up being ejected from the vessel. The four Mario Bros. land in Toad Town and from there, travel to Star Hill.

There they find the Commander Shroob, his team of Support Shroobs, and a Shroob-omb who engage them in battle. Once Commander Shroob and his team are defeated, the four heroes head to the top of Star Hill where the protagonists talk to the Cobalt Star's Spirit which tells them that when the find five out of the six parts of the Cobalt Star, they can enter Shroob Castle.

The heroes head to the Star Shrine, where another Cobalt Shard is located. The brothers then meet up with Toadbert and Kylie Koopa, who now knows how to clean Toadbert's picture, revealing the depiction of a second Shroob princess. Their group is attacked by the Elder Shrooboid, which turns Toadbert and Kylie into Shroob Mushrooms before it could be stopped by the Mario Bros. After collecting another Shard from the vanquished Shroob, the Mario Bros. travel to the Shroob Castle in the past by way of the future castle and its many time holes. Mario and the gang take down the Shroob Mother Ship and finally find Princess Peach being held captive by Princess Shroob, who they battle and defeat. Peach shows them the final piece of the Cobalt Star but won't let them merge it with the other pieces, however before she can explain why, Baby Bowser swoops in and completes the Cobalt Star himself, releasing the Elder Princess Shroob, who had been trapped in the star by Princess Peach. Baby Bowser is turned into a Shroob Mushroom for his troubles and Elder Princess Shroob attacks the Mario Bros. next, but they defeat her and she transforms into a purple mushroom.

Baby Luigi cries on the Shroob Mushroom that used to be Baby Bowser after Baby Mario accidentally Ground Pounds him, restoring his former self. Professor E. Gadd then uses his Hydrogush 4000 invention to sprays a liquid with the same chemical makeup as baby tears all across the Mushroom Kingdom of the past, restoring everyone else who had been affected by the Shroobs. The Mario Bros. discover Bowser unconscious in Peach's Castle in the present and Elder Princess Shroob's mushroom flies into his mouth, turning him into Shrowser for one last attack on the Mario Bros. After Shrowser is beaten and the Shroob threat is finally put to rest forever, Toadsworth the Younger, Baby Peach, Baby Mario, and Baby Luigi all use the repaired time machine and travel back to their own time, bidding farewell to their future selves.

Battle system
To start a battle, Mario, Luigi, or their baby selves must touch an enemy or perform a First Strike by jumping on or hitting the enemy with a hammer in the overworld. A first strike damages the enemy (if jumped on) or possibly stun them (if hit with a hammer) as the battle starts. If an enemy with spikes or fire is jumped on, the brother who jumped on the enemy is damaged. Additionally, if the enemy starts the battle by hitting a Bro. in the back, that brother cannot move until his turn. Since the game is a turn-based RPG, the player and enemies take turns attacking each other; the brothers use Command Blocks as the interface to select actions. The player can use well timed attacks to deal more damage. The player can also counterattack the enemy to damage them (see below). The enemies never counterattack but can harm the brother if they have spikes or are on fire and are jumped on, though these elements cannot KO a brother, even if he has one HP left.

When a brother's HP hits zero, he passes out and remains in this state until the end of the battle (where he has one HP in the overworld) or if he is revived with a 1-Up Mushroom. If the babies and adults are separated from each other, the surviving brother carries the passed out one, though it greatly hinders on the surviving brother's ability to avoid enemy attacks. If the brothers are in Piggyback Mode, the adults take all damage from enemy attacks until they pass out, where the baby takes the passed out brother off-screen and fights on his stead. If the baby also passes out, the surviving brother pair carries him, also hindering their ability to avoid enemy attacks. If all in-battle brothers' HP reach zero, regardless if there are non-fighting brothers in the overworld, the player gets a Game Over and either restarts from the last save point or returns to Princess Peach's Castle.

If all enemies' HP are reduced to zero, the battle is won and EXP points and coins are gained. Depending on the enemy defeated and what badges are worn, regular items, Bros. Items, Clothing, and Badges may be won as well.

Stats
Each brother has his own HP, POW, DEF, SPEED, and STACHE points. With enough EXP Points, a brother can level-up and increase each respective statistic. Mario, Luigi, Baby Mario and Baby Luigi lean towards certain stats: Mario and Baby Mario have increase in stats that favor of power and speed while Luigi and Baby Luigi's stats generally favor HP, defense, and stache. The babies have generally weaker stats than their adult counterparts barring their speed, where they outperform their adult counterparts at. Clothing and some badges can also alter a brother's stats.

Moves
During a battle, the four brothers have five choices when attacking, unless Mario and Luigi are not paired with the babies; instead, they would have four choices. They can use a jump move, a Hammer move, a Bros. Item, use an item, or run from battle.

Jump move
During a jump move, a brother jumps on an enemy. When Mario jumps on an enemy, he uses, for Luigi,  on Baby Mario, and  for Baby Luigi's jump. Hitting their button when they are about to land on the enemy does extra damage. The babies can participate in battle, assisting their older counterparts. If so, when the two older bros. attack and land on an enemy, the player should press the babies button, and then the adult brother's button. This deals more damage to the enemy.

Hammer move
After Baby Mario and Baby Luigi enter the Vim Factory, they get hammers to use in battle. However, the adult Mario and Luigi cannot use this move without the babies with them, as they do not have hammers. When one of the babies attack with a hammer, the player must hit their button (either or ) when the tool shakes to deal more damage. If the player waits too long or hits the button too early, the hammer head falls off the hammer and the baby brother does much less damage. When the corresponding button is hit before they directly face the enemy, they trip and fall flat on the enemy, also yielding less damage. When the adult bros. are with the babies, they can perform a stronger attack with them. When doing this, the player must hit the adult button ( or ) to have Mario or Luigi lift up the baby. Then, they must hit the baby button ( or ) when their hammer shakes. This deals more damage than a normal hammer attack. The hammer move does less damage than a jump move, and it is best used when fighting a spiked enemy. Flying enemies avoid the hammer altogether.

Bros. Items
Bros. Items are special attacks that the brothers can use to deal more damage. Some Bros. Items require at least two brothers standing while some require all bros. Some items that require two bros. have special commands that can be used to deal more damage than normal with all four bros. Note that some items are unlocked later in the game than others.

Items
When choosing the item icon, the four heroes can use an item to recover HP. Other items, such as Refreshing Herbs, can heal status effects. When one of the bros. passes out, the other bros. can use a 1-Up Mushroom or 1-Up Super to revive him. However, once an item is used, the bro.'s turn is over. Peppers are another type of item that can be used with this icon and can temporarily increase the bros. stats.

Flee
Mario, Luigi, and the babies can both flee from battle when they choose the flee icon. When getting away, the player must hit either the or  button to make Mario or Luigi flee. If the babies are in battle, the player must hit the or  button. However, if they do not do this quickly, one of the bros. falls and drop a large amount of coins unless a wallet badge is equipped. When both bros. have left the screen, they end up back in the overworld and continue their adventure. The player can cancel this attempt by pressing the button, though it uses up a turn. This cannot be used in Boss Battles.

Avoiding attacks
Mario, Luigi, or Baby Mario and Baby Luigi can either use their Hammer or Jump moves to avoid attacks. With their Jump move, the brothers can jump over the attacking enemy. When using the Hammer to avoid attacks, the player must hold Baby Mario or Baby Luigi's respective button (Baby Mario is, Baby Luigi is ) and release just as the enemy or its weapon hits.

The four bros. can also use these moves to counterattack. When they jump over an enemy, they may land on them, causing damage. Baby Mario or Baby Luigi can also hit enemies with their hammer during an enemy's turn. Either way, the enemy takes damage on its turn.

Altered states
Altered states return from Mario & Luigi: Superstar Saga, with the same conditions that can cause it. Certain enemies have attacks that can cause altered states, which hinder a brother in a way. The brothers can also inflict altered states on enemies as well with the Bros. Flower, Ice Flower, and Mix Flower, as well as enhancing their stats with peppers. Over a period of time, altered states wear off, though the brothers can recover quicker from negative altered states if they use a Refreshing Herb.

Field features
On the overworld, the brothers can navigate their environment. They can interact with a variety of objects such as blocks and switches and use various techniques to help with their progress of the game. During normal overworld progression, the DS bottom screen displays character control and progress while the top screen displays the map, character HP, coins, and where the brothers are currently located, alongside miscellaneous map features. When the babies are sent to locations only they can access, such as going down a hole or using a Trampoline, the top screen changes from the map to display the babies' control and progress.

Techniques
The brothers can use some techniques out of battle. All of the following techniques must be learned by progressing in the game, except for jumping. Each button is assigned to each brother, with being Mario's button,  being Luigi's,  being Baby Mario's, and  being Baby Luigi's. Players can switch action commands with  and, demonstrated by the changing of the action icons, as soon as they learn different techniques. Unlike in Mario & Luigi: Superstar Saga, players cannot switch the order of the brothers; Mario or Baby Mario is always the leader.

In the middle of action commands, players can cancel them by pressing the corresponding button that has "BACK" displayed on it.

Mario and Luigi techniques
When Mario and Luigi are without the babies outside of battle, they can do the following techniques:

Baby techniques
When Baby Mario and Baby Luigi are alone outside of battle, they can do the following techniques:

All-character techniques
When all four bros. are together, they can perform the following techniques:

Enemies
Some enemy stats vary between versions. The first number is from the North American version and the number in parentheses is from the European and Japanese releases.

Minigames
Along the quest, the brothers can play various minigames. These minigames are required to complete for the brothers to progress in the game. The Thwomp Caverns minigame can be replayed; the second spaceship minigame of the Shroob Castle can also be replayed, as it is part of the final levels of the game, where Stuffwell can use his Special Service Warpulator to warp back before that point.


 * At Thwomp Caverns, located in the Thwomp Volcano, the Thwomp Bros. host two minigames. The older Thwomp Bros. operates a slot machine. In order to use it where Mario and Luigi need to roll into Bros. Ball and collect as much jewels as possible. If enough jewels are collected, Baby Mario can stop the slots with his hammer. Depending on the difficulty setting and the slots aligned, the brothers can receive various items as rewards, including coins or beans.
 * The other minigame is hosted by the younger of the Thwomp Bros. In this minigame, Mario and Luigi must use the Baby Spin on Baby Mario and Baby Luigi for them to use a Whirlwind. On their descent, they need to collect as many jewels as possible, with the prizes dependent on the number of jewels collected.
 * In the Shroob Castle, two minigames involving a spaceship is played. The first minigame involves piloting the Shroob Mother Ship in order to take down smaller Shroob UFOs; the other, later minigame involves using the head of the Princess Shroob statue of the spaceship to shoot Shroob UFOs into the Shroob Mother Ship to destroy it. In this minigame, the height of the spaceship is controlled by Luigi, Baby Mario, and Baby Luigi hitting blocks, where the spaceship rises to the height in tandem with the rising and falling bar. Hitting the block stops the bar, which indicates the height the ship will rise to. Mario's block fires a laser beam, used to attack Shroob UFOs. Once Mario fires his laser, the height of the ship resets to the bottom. All characters are not required to hit the block for Mario to use the laser. In the second spaceship minigame, the ship the brothers are piloting have a set number of hit points, which get decreased when a Shroob UFO runs into it. When all hit points for the player are depleted, the ship crashes and the player gets a Game Over.

Shops


Four shops are found in Mario & Luigi: Partners in Time. One, the Shroom Shop, is found in the main hub in Princess Peach's Castle. The rest are found in levels throughout the game. Fawful's Bean 'n' Badge sells Badges exclusively at a price of beans rather than coins.


 * Shroom Shop, located in Princess Peach's Castle
 * Monty Mart, located in Gritzy Caves
 * Gramma's Place, located in Toad Town
 * Fawful's Bean 'n' Badge, located in Peach's Castle Dungeon

Clothing
Clothing boosts the brothers' stats. There are two categories of clothing: one made specifically for the adult brothers and one made specifically for the baby brothers. Unlike Mario & Luigi: Superstar Saga, clothing is not restricted to a specific brother. Clothing is either dropped by enemies, found in blocks, or purchased in shops.

Badges
Badges cause miscellaneous effects when worn and can be universally worn by all brothers. Such effects include unlimited use of Bros. Items or restoring HP every turn. They do not increase a brothers' base stats. Badges can be purchased in shops, exclusively purchased in Fawful's Bean 'n' Badge, dropped by enemies, or won by completing minigames.

Notable mistakes and errors

 * In the North American instruction booklet, page 27 has a Japanese screenshot, where "Stache" is listed as "Hige".
 * In the North American instruction booklet, page 32 has the following sentence: "Approach either side and speak to the sales-Toad to make the corresponding menu will appear," where the word will is an unnecessary addition to the sentence structure.

Staff
AlphaDream developed the game, as they did with other games in the Mario & Luigi series. Shigeru Miyamoto and Tetsuo Mizuno produced the game, with Satoru Iwata as the executive producer. Yoko Shimomura, who composed music for the other Mario & Luigi games and Super Mario RPG: Legend of the Seven Stars, also composed music for this game.

Critical reception
Mario & Luigi: Partners in Time has received generally positive reviews from critics, with it having an average score of 86 from Metacritic based on 45 reviews and a GameRankings score of 85.23% based on 55 reviews. Critics generally praise the humor, characters, and graphics of the game, as well as its use of the dual screen and its rumble feature. Several criticisms include the long, drawn out boss battles and the difficulty coordinating the game's four characters.

Craig Harris of IGN has lauded the game, giving it a nine out of ten. He praised the gameplay, the difficulty curve, the humor, and the two-screen display, but has commented that the beginning of the game starts off too easy. Thomas Bowskill of Nintendo Life has also given the game a 9/10, also praising the gameplay, the comedy, and the sound, but added that the game is not replayable and how actions in the past do not influence the future. Jonathon Metts of Nintendo World Report gave the game an 8/10, states that while the flawed battle system smears his opinion of the game, he states that it is "the best RPG currently on the Nintendo DS."

Sales
The game has sold 132,726 on its opening week in Japan, ranked number seven as reported by Gamasutra. The game has a worldwide sales of 1.39m units as reported by IGN.

Super Mario-Kun adaptation
Mario & Luigi: Partners in Time has been adapted into the Super Mario-Kun manga, written and illustrated by Yukio Sawada. The story arc related to Mario & Luigi: Partners in Time spans across three volumes: volumes 35, 36, and 37. Though it follows the source material, it introduces various key story element differences, as every Super Mario-Kun volume adaptation of their respective game.

Differences in the Super Mario-Kun manga

 * Luigi is involved in the Junior Shrooboid boss fight, though against his will; Mario uses him as a weapon to defeat the Junior Shrooboid.
 * All Shroobs are able to speak coherently from the beginning, including Princess Shroob.
 * Although Mario and Luigi do arrive at the Hollijolli Village, they do not encounter the Hollijolli Mayor. Instead, the Shroobs engage them immediately and defeat them.
 * Bowser's Castle does not appear at all. After the Mario Bros. encounter the Baby Mario Bros., they travel to the Shroob Castle.
 * Snoozorbs, which are late-game enemies, appear relatively in the beginning of the Super Mario-Kun; the brothers fight it when they arrive to the Shroob Castle.
 * The Snoozorb fight teaches Mario and Luigi the technique of the Bros. Ball, where they use it as an attack rather than a utility move for transportation. Later in the story arc, a four-brother version of the ball is used against the Elder Princess Shroob.
 * Though it is discovered that Toads are being used for fuel in the Toadwood Forest and Vim Factory, Toadiko does not appear.
 * Baby Mario and Baby Luigi receive their hammers from supplies that Toadsworth the Younger provides, while the Hammer Bros. do not appear at all. As a result, Mario and Luigi do not get captured in the Vim Factory.
 * Toads do not get their energy sapped from being strapped onto trees. Rather, Swiggler sucks their energy directly from them.
 * Baby Luigi carelessly spinning around with his hammer gives Baby Mario the inspiration for the Baby Drill move, where it is used as an attack, similar to the Bros. Ball, rather than the Hammer Bros. teaching the move to them.
 * The Yoob is a friendly giant, hungry Yoshi who gets taken over and manipulated by Sunnycide. Other Yoshis and Toadbert do not appear.
 * Neither Kylie Koopa nor the Koopaseum appear in the manga. Rather, the four brothers travel to Gritzy Desert and eventually take a Warp Pipe down to Gritzy Caves.
 * Petey Piranha is portrayed as a female character, alongside Piranha Plants (called bero pakkun, which roughly translates to "Tongue Piranhas") with a Cobalt Star Shard as part of her teeth.
 * The characters do go to Thwomp Volcano and fight Mrs. Thwomp, but do not enter Thwomp Caverns, nor fight Baby Bowser and Bowser. In fact, Bowser does not appear at all in this story arc.
 * The Star Hill is portrayed as a snowy location, where Baby Luigi rebuilds a destroyed Snowman. The Snowman later helps the brothers fight the Commander Shroob, the Shroob-omb, and the Support Shroobs, though the Commander Shroob destroys it. As a result, it gives Baby Luigi an Ice Flower, which helps him defeat the Commander Shroob and his army.
 * At the Star Shrine, Luigi proves his worth by using a Copy Flower on the Piranha Planet and defeating it, while also obtaining the Aurora Block.
 * An entire chapter is devoted to the Marios and Luigis fighting each other, due to the deception of a Tanoomba.
 * The Shroob Mothership is taken down due to Baby Mario tricking Princess Shroob with a false mail delivery.
 * The Princess Shroob is the character who fully assembles the Cobalt Star together, rather than Princess Peach holding on to the last Cobalt Star Shard and Baby Bowser intervening.
 * The Princess Shroob and Elder Princess Shroob fight simultaneously, though the Princess Shroob mostly stays on the sidelines.
 * A chapter is devoted to Toadsworth and Toadsworth the Younger taking care of Baby Peach, when a Shroobsworth and an Intern Shroob appears and attacks them. The two Toadsworths intervene to defend Baby Peach from their attacks, until E. Gadd gives Baby Peach Perry, the parasol. The parasol causes Baby Peach to activate her anger vibe, thus defeating the two enemies. These actions reference Super Princess Peach.
 * Baby tears weaken the Elder Princess Shroob, though a rainbow shell is the item that ultimately defeats her.
 * Mario and Luigi are the characters who leave with the time machine, rather than the past versions of the characters leaving.
 * Shrowser is referenced in the epilogue to the story arc, where Baby Bowser eats the purple mushroom containing the essence of the Elder Princess Shroob. He battles the Baby Mario Bros., but before the Baby Mario Bros. retaliate, he poops the Elder Princess Shroob mushroom.

References to other games

 * Super Mario Bros. - When the wind blew away Baby Peach, Toadsworth the Younger asked the Baby Mario brothers to save her, saying: "You will save her, won't you? I assure you, she's NOT in another castle or anything." This is a reference to the repeated Toads' line: "Thank you, Mario! But our princess is in another castle!" Also, when traveling through a time portal, a remix of the underwater theme from this game plays.
 * Super Mario All-Stars - One of Shrooboid Brat's attacks involves having the audience giving him either fire flowers, mushrooms, or poison mushrooms. The poison mushrooms' appearance is exactly the same sprite of their appearance in the remake of Super Mario Bros.: The Lost Levels.
 * Yoshi's Cookie - The cookies in Yoshi's Island reappear.
 * Super Mario World 2: Yoshi's Island - This game features the return of Baby Mario, Baby Luigi, Baby Bowser, and the Chomp Rock. Also the player can travel to Yoshi's Island, whose first area has the same music as this game's alternate title music. In addition, Kamek makes a reference to his attempted kidnapping of Baby Mario and Baby Luigi in Super Mario World 2: Yoshi's Island.
 * Super Mario RPG: Legend of the Seven Stars - In the beginning of the game, the Cobalt Star shard is in a block similar to the regular Treasure Chest blocks in this game.
 * Super Mario 64 - The music that plays within Princess Peach's Castle is a cover of "Inside the Castle Walls".
 * Luigi's Mansion - Professor E. Gadd moves to the Boo Woods as a young man where he is later found by Luigi, foreshadowing the events of the game. Also, music from cutscenes involving E. Gadd are a cover of the Luigi's Mansion main theme.
 * Super Mario Sunshine - Shine Sprites return as a source of light. Also, the Hydrogush 4000 resembles F.L.U.D.D.. Petey Piranha appears as a boss.
 * Mario Kart: Double Dash!! - Some of the voices are re-used from this game.
 * Mario & Luigi: Superstar Saga - Fawful runs Fawful's Bean 'n' Badge. Additionally, a picture of Prince Peasley appears in the Shroom Shop on a poster about beans. The ending theme for Mario & Luigi: Partners in Time is a cover of the ending theme from Mario & Luigi: Superstar Saga. Also, before the fight with Bowser and his younger self, Bowser affectionately calls Baby Bowser a 'little Firebrand', Mario's skill from said game. When fighting the Hammer Bros in the Vim Factory, they use an attack that is identical to the Bros. move, "Knockback Bros", preformed by Mario and Luigi in Mario & Luigi: Superstar Saga. Also two enemies, Trunkle and Mecha-Chomp have similar battle style to Mrs. Thwomp and Shroid respectively. Also, during the battle with Elder Princess Shroob, one of her attacks involves striking her own UFO's with fire and lightning to attack the Bros. UFO's on fire hit Mario, while those struck by lightning hit Luigi, referencing the Firebrand and Thunderhand skills from said game.
 * Paper Mario: The Thousand-Year Door - Dark Boos first appeared in this game. Toadsworth the Younger also references the Bristle enemy that has only appeared in this game while admonishing his present day counterpart.

References in later games

 * Super Smash Bros. Brawl - A Shroob, Stuffwell, and Luigi carrying Baby Luigi appear as stickers. Also, a cover version of the Gritzy Desert theme returns for the Mushroomy Kingdom stage. The boss theme was originally going to be in Super Smash Bros Brawl, but was removed in the final version. One of Luigi's poses in this game resembles his artwork for Mario & Luigi: Partners in Time.
 * Mario & Luigi: Bowser's Inside Story - Three Shroobs appear as optional bosses. Junior Shrooboids, Commander Shroobs, and Elder Princess Shroob cameos in the background of that stage. Also in the audience from Fawful Theater there's a Shroob in the audience. There are some gear that has "Shroob" in the name.
 * Mario & Luigi: Dream Team - Kylie Koopa appears in this game, along with a picture of a Shroob hanging on a wall in the house where she is found.
 * Super Smash Bros. for Nintendo 3DS / Wii U - One of Luigi's poses in this game resembles that of his solo artwork from Mario & Luigi: Partners in Time.
 * Mario & Luigi: Paper Jam - Petey Piranha returns as a boss in this game. Also, a cover version of Peach's Castle can be heard. Finally, the tutorial theme in Mario & Luigi: Paper Jam is a cover version of Mario & Luigi: Partners in Time's tutorial theme.

Pre-release and unused content
A pre-release screenshot depicts Mario, Luigi, and their baby selves fighting two red shoe-clad Blooper foes (called Scoot Bloops) in the Vim Factory. Unfinished code for the Scoot Bloops remain the final build of the game. There are also screenshots of the four brothers using what appears to be a purple Spiny Shell as a Bros. Item. This item would act like a Koopa Shell, but would be hammered instead of kicked.

Quotes

 * "I'm afraid our dear Toadsworth has worried himself into a state of shroomshock." -Dr. Toad
 * "BACK TO ADVENTURE!" -Stuffwell
 * "I say to you WELCOME! Welcome to Fawful's Bean 'n' Badge!" -Fawful
 * "You are true and courageous. Your heart is filled with virtue and concern for your brother. I do recommend you watch your diet, however it is also filled with much Alfredo sauce. You should especially cut down on carbora, though it will be hard, for that is very tasty. If you curb your appetite, do some light cardio work and continue to ward your brother, you will no doubt grow to be a figure of immense popularity, yet not grow an immense belly. You may pass and I do recommend puttanesca; that stuff is great." -Star Gate
 * "AREA RESTRICTED. ALL NOOB INTRUDERS 2 B HAXORED BY US L33T HAMM3R BROZ.!" -Hammer Bro

Wii U eShop description
''Twice the Bros., twice the insanity! In this quest of lunatic proportions, the Mario bros. team up with none other than... their younger selves! Control both sets of bros. at once in this intriguing action RPG, where comedy is king and the story leads you beyond the Mushroom Kingdom. Explore Mario’s world across space and time as you take down the evil alien invaders, the Shroobs! In this precursor to the Mario & Luigi™: Bowser's Inside Story game, the brothers travel back in time to retrieve Princess Peach™, only to come face-to-face with baby versions of themselves, the princess, and Bowser™. While controlling both the adult AND baby versions of the Mushroom Kingdom heroes, you’ll unleash powerful attacks and cross environments using special techniques to solve puzzles in creative ways. With four brothers to control, this adventure is bound to get out of control!

Trivia

 * The solo artwork for Baby Mario incorrectly depicts him with red shoes, instead of light-blue. Other artwork depicts him with the correct light-blue shoes.
 * This is the only Mario & Luigi game to lack a BP stat (or its variations).