First Seen: Wii Sports (2006)
Miis are digital avatars that appear in various games released on Nintendo platforms including the Wii, Wii U, Nintendo 3DS and Nintendo Switch. Players can design what their Miis look like and use them to represent themselves or others in many games and online services, as well as share them with other players.
Miis appear as playable characters exclusive to the Wii version of Sonic & Sega All-Stars Racing. Miis are silent and drive the Super Zoomer, and their All-Star Move is Parade Power, which summons four Miis to carry the car at high speed. They return in Sonic & All-Stars Racing Transformed as exclusive characters to the Wii U and 3DS versions of the game, where their Super Zoomer is now modelled after an OutRun-style car, they now have a voice, and their All-Star Move makes swords and shields appear around their vehicle.
Miis also appear as playable characters in the console versions of Mario & Sonic at the Olympic Games and all of its sequels. Miis are generally all-around characters with equal stats across the board and no voices. From Mario & Sonic at the Olympic Winter Games onwards, the player can buy clothes and accessories, including costumes based on various Mario and Sonic characters, for the Miis that also affect their stats. In Mario & Sonic at the Rio 2016 Olympic Games, they are playable in both the console and handheld versions of the game, being one of three characters who can be used in any event in the 3DS version and being the primary character in the Road to Rio mode.
While technically not Sonic games, Super Smash Bros. for Nintendo 3DS and Wii U feature Miis as playable Mii Fighters with Mii Brawler, Mii Gunner and Mii Swordfighter classes to choose from. The player can not only customize their special moves, but also their appearance using costumes unlocked via play or by purchasing DLC, with two downloadable costumes being based off Tails and Knuckles. The Tails costume is compatible with Mii Gunners, while the Knuckles costume is compatible with Mii Brawlers.