Bowser

Mario's scaly nemesis is a turbo beast in any race, but he takes a while to reach top speed. Bowser returns as a heavy racer. He has one of the best speed and weight boosts in this game. His Koopa Clown Car, renamed as the Koopa Clown, is an unlockable kart part. He has a new track in the Star Cup, Neo Bowser City, a track in the Special Cup, Bowser's Castle, a track in the Shell Cup, GBA Bowser Castle 1, and in the Lightning Cup, there's DS Airship Fortress. Bowser has the most courses belonging to him than any other character in this game.