Tails

Miles Prower, better known by his nickname "Tails", is an eight-year-old, two-tailed yellow fox from the  franchise, and the sidekick and best friend of Sonic. He is a mechanical genius who has the ability to spin his tails like a propeller, and thus fly. In Mario & Sonic at the Olympic Games and Mario & Sonic at the Olympic Winter Games, he is voiced by Amy Palant, but in Mario & Sonic at the London 2012 Olympic Games until 2014, he has been voiced by Kate Higgins. He is now voiced by Colleen Villard. "Miles Prower" is a pun on "miles per hour".

Mario & Sonic at the Olympic Games
Tails participates in Olympic events in Mario & Sonic at the Olympic Games. He is a Skill type player, with skill and stamina being his best stats. Ironically, he is quite slow in this game, while he is quite speedy in the Sonic games.

Mario & Sonic at the Olympic Winter Games
Again, Tails participates in the Olympic events, this time in Mario & Sonic at the Olympic Winter Games, the sequel. Tails is a Skill type player again. His stats are given on the official site as well.

Tails made an appearance in the adventure mode of the game for the Nintendo DS. In the game, he decides to help Sonic and Mario on their quest. Tails even makes remarks about Mario when he and Sonic first meet the fox, showing that Tails respects Mario due to his heroism (similar to how he respects Sonic).

Mario & Sonic at the London 2012 Olympic Games
Tails returns as a playable Skill type character in the Wii version of Mario & Sonic at the London 2012 Olympic Games, and appears in the opening with all of the other athletes, as well as competing in Uneven Bars and Dream Hurdles. Tails appears as one of the characters that can be spoken to in order to play a minigame and earn stickers in London Party mode, and a Mii outfit based on Tails an be unlocked.

In the Nintendo 3DS version, Tails is included in the Heroes group, meaning that he is only playable in certain Events. In the Story Mode, Tails first appears alongside Sonic when they arrive at the Tower of London and find red Phantasmal Fog, which they clear up and conclude that Bowser is involved with it. The next day, the pair head to Tower Bridge, where they find more Phantasmal Fog and clear it up with the help of Yoshi, Shadow, Silver and Jet, allowing the bridge to be lowered. They also learn from Bowser Jr. that Dr. Eggman is also partly responsible for the fog, so Tails and Sonic head to the British Museum to continue investigating. At the museum, Tails and Sonic find and team up with Mario, Luigi and Toad, and the group clear the fog from the area and head into the museum to find some more information about the Phantasmal Fog, which Tails manages to do. The group then splits up, with Tails following Espio to ExCeL London where they find that Omega has had a chip installed by Dr. Eggman, and remove it with Donkey Kong's help. Tails, Espio and Omega then head back to the Main Stadium, and Tails helps rescue Cream from some Fog Imposters when the fog returns. Tails then heads to Stonehenge with Mario, Luigi, Toad, Sonic and Omega, where they find the lid for the Fog urn and learn from Omega that Bowser and Dr. Eggman are hiding inside Big Ben. The group head there, and Toad passes the walkie-talkie onto Tails before he and Omega leave the group. The Heroes head into Big Ben to confront Bowser and Dr. Eggman, and after they have been defeated, Tails goes with them to the Main Stadium so that they can register for the Olympic Games, later appearing at the opening ceremony. A badge of Tails can also be obtained from the badge machine.

Mario & Sonic at the Sochi 2014 Olympic Winter Games
Tails appears in Mario & Sonic at the Sochi 2014 Olympic Winter Games. Like previous games in the series, Tails is a playable Skill type character.

Mario & Sonic at the Rio 2016 Olympic Games
Tails returns in Mario & Sonic at the Rio 2016 Olympic Games as a Skill type character once again. In the Nintendo 3DS version he's exclusive to 100m Freestyle and Beach Volleyball.

Mario & Sonic at the Olympic Games Tokyo 2020
Tails reappears in Mario & Sonic at the Olympic Games Tokyo 2020 as a playable character. Like many other characters in the game, Tails wears outifts that are event-appropriate. He is also one of the eight characters playable in 2D events. He plays a role as a major playable character in the Tokyo 2020 parts of the Story Mode.

Super Smash Bros. Brawl
In Super Smash Bros. Brawl, Tails appears in the background of the Green Hill Zone stage as a cameo. He can occasionally be seen running through the loop in the background, alongside fellow Sonic characters Knuckles the Echidna and Silver the Hedgehog. Tails also appears in the form of a collectible trophy and Sticker.

Super Smash Bros. for Nintendo 3DS / Wii U
Tails reprises his role from Super Smash Bros. Brawl in Super Smash Bros. for Nintendo 3DS, running in the background of Green Hill Zone, along with Knuckles the Echidna and Silver the Hedgehog. Tails makes an appearance as a Trophy in both versions of the game. An outfit based off of Tails appears as a DLC outfit for Mii Gunners in both versions. It was released in February 2016, alongside a Knuckles outfit.

Super Smash Bros. Ultimate
In Super Smash Bros. Ultimate, Tails once again appears in the background of Green Hill Zone alongside Knuckles and Silver. He also appears as a Spirit.

Profile
''Sonic's buddy Tails the fox can fly thanks to his bushy tails, and he possesses a wide range of Skill-based abilities that will make him formidable in a wide range of events. He can jump and accelerate well, so he will be tough to beat in many races.''

Profile
''Miles "Tails" Prower is Sonic's best friend and always at his side. An ace pilot and mechanic, Tails returns to the Olympic Games with the Tailspin ability on the Wii and DS to spin his tails like a helicopter and propel himself in the air, as well as the Propeller Dash ability on the DS.''

Profile
''Sonic's best friend and buddy Miles Tails Prower is a fox that can fly, thanks to his bushy tails, and he possesses a wide range of Skill-based abilities that will make him formidable in a wide range of events. He can jump and accelerate well, so he will be tough to beat in many races.''