Alex
From the Super Mario Wiki
Alex is a character in the Game Boy Color version of Mario Tennis.
He is a playable character in GBC Version of Mario tennis, his partner is Harry. In the game, everyone at the Academy is surprised at his very fast rise in the club ranks by getting into the varsity team by beating the 4th placed Bob, after a few days of just being instated. He beats Emily on the way to the final against Factory's A. Coz, where Alex wins easily. After hearing of the newest tennis star, Princess Peach invites Alex for a match against Mario.
In the GBA version, he is the Academy's best player and is still the only one that has challenged Mario before. At the start of the game, Alex loses the match against Mario, who's wearing a mask to protect his identity. Alex says that he is surprised that he came back for a rematch and wonder when he'll be seeing him again. When Clay or Ace leaves for Isle Delfino after winning the Island Open, Alex will tell him a bit about his experience against Mario and expects the player to beat Mario.
Alex cannot be faced in the GBA version.
