Galaxy Arena

Galaxy Arena is a galaxy-based court in Mario Tennis Open. It has objects from Super Mario Galaxy, such as Shrinking Tiles, a Launch Star, Star Bits, a planet from the Gateway Galaxy, a Black Hole, Turquoise, Red and Green Lumas, and the whole Comet Observatory in the distance. The special game Galaxy Rally is played on this court, where the Star Chips appear on the court, and the player may try to collect them by hitting the tennis ball at them to receive coins. It is an unlockable stage, and it can be unlocked by completing the Final Cup in the Star Open Tournament.

The unlockable stage has differences to the one played in Galaxy Rally; it lacks disappearing green platforms and it takes place in an another location. Also, it has max bounce and max speed. There are two varieties to this court: the Morph and the Crystal court. The Crystal court plays normally, but the Morph court has an added gimmick. When a player performs a chance shot, and the ball hits the ground, the type of floor on the opponents court changes to various patterns from other courts in this game, which affect ball velocity and bounce. A unique floor, a black hole pattern, erratically alters the direction of the ball bounce into one extreme direction. Only one part of the court can get altered: the player must perform a chance shot to change the pattern in the opponents court and the player must perform a chance shot to remove the court's current pattern.