Island Open

The Island Open is the big tournament in Mario Tennis and Mario Tennis: Power Tour. The tournament itself is divided into singles and doubles tournaments between the Academy, the Union, the Empire, and the Factory.

Game Boy Color
Each match is 5 sets and 6 games long. Unseeded players must start in round one while seeded players are given a bye to round two.

Singles
In singles, the player will battle in order: Sammi, Spike, Emily, and lastly A. Coz.

Doubles
In doubles, the player's team will battle in order: Sammi and Sean, Spike and Elden, and lastly A. Coz and B. Coz.

Game Boy Advance
Each match is 5 sets and 2 games long. In singles, unseeded players must start in round one while seeded players are given a bye to round two. In doubles, as there are a balanced number of teams, all teams start in round one. Dweezil is the defending champion of both the singles and (along with Mynx) the doubles championships.

Singles
In singles, the player will battle in order: Barb, Sass, Elroy, and lastly Willy.

Doubles
In doubles, the player's team will battle in order: Chas and Mel, Dweezil and Mynx, and lastly Willy and Sheri.

Trivia

 * In Mario Tennis: Power Tour, it is shown that Alex is canonically the winner of the singles and (along with Harry) the doubles championships of the Island Open.
 * In both games, the only Union player to make it past round one is Chas.
 * The singles championship of Mario Tennis: Power Tour is the only time the player is not on the top-left of the bracket.
 * As there are no mentions of any third-place matches, the third place trophies go to the higher ranked players. Kevin and Emily should have gotten a third place trophy for doubles in the Game Boy Color version, but likely due to graphical limitations, only first and second place were shown.