Island Open

The Island Open is the big tournament in Mario Tennis and Mario Power Tennis. The tournament itself is divided into singles and doubles tournaments between the Academy, Factory, Empire, and Union. In the Game Boy Color game, the amount of students from each school was uneven, but that was changed in the Game Boy Advance game.

Singles Players by School (Game Boy Color)

Academy
 * Alex or Nina
 * Emily (semifinal opponent)
 * Kevin (never faced)
 * Mark (not faced in the tournament)

Factory
 * A. Coz (final opponent)
 * B. Coz (not faced in the tournament)
 * Frank (never faced)

Empire
 * Spike (round 2 opponent)
 * Ellis (never faced)
 * Elden (not faced in the tournament)

Union
 * Sammi (round 1 opponent)
 * Sean (not faced in the tournament)

Doubles Teams by School (Game Boy Color)

Academy
 * Alex or Nina, Harry or Kate
 * Kevin, Emily (not faced in the tournament, Kevin never faced)

Factory
 * A. Coz, B. Coz (final opponents)

Empire
 * Spike, Elden (semifinal opponents)

Union
 * Sammi, Sean (round 1 opponents)
 * Ellis, Edgar (never faced)

Note: Whether the Ellis from Empire in the singles tournament is the same person as the Ellis from Union in the doubles tournament has yet to be confirmed.

Singles Players by School (Game Boy Advance)

Academy
 * Max or Tina
 * Elroy (semifinal opponent)
 * Whisker (not faced in the tournament)

Factory
 * Willy (final opponent)
 * Sheri (not faced in the tournament)
 * Sass (round 2 opponent)

Empire
 * Dweezil (not faced in the tournament)
 * Mynx (not faced in the tournament)
 * Barb (round one opponent)

Union
 * Chas (not faced in the tournament)
 * Mel (not faced in the tournament)
 * Leon (never faced)

Doubles Teams by School (Game Boy Advance)

Academy
 * Max and Tina
 * Elroy and Tori (not faced in the tournament)

Factory
 * Willy and Sheri (final opponents)
 * Sass and Chet (not faced in the tournament, Chet never faced)

Empire
 * Dweezil and Mynx (semifinal opponents)
 * Barb and Oscar (not faced in the tournament, Oscar never faced)

Union
 * Chas and Mel (round one opponents)
 * Leon and Peter (never faced)