Kevin

Kevin is a non-playable character in Mario Tennis and Mario Power Tennis. In the Game Boy Color game, he is the highest-ranking player at the Academy, although that changes once Alex or Nina (depending on the player's choice) wins the Island Open. In the Game Boy Advance game, he's the coach of the Academy's Varsity Class.

Knowing how hard it is to reach the top, he takes a more realistic approach to tennis than Mark and Emily, rarely speaking optimistically even in the face of a victory, although he does not speak pessimistically to players, either. He takes his job--and that of his students--very seriously. Even after Max or Tina wins the Island Open, he does not act impressed, saying that most people will view the victory as a fluke unless they win again the following year--which cannot be done in the game.

Trivia

 * Although Kevin is a non-playable character in both games of appearance, the Japanese version of Mario Tennis features a full, working, playable character sprite set for Kevin in the game's data. This can only be accessed through means of game modifying hardware. All graphics of Kevin's were removed from the US and EU versions of the game.