Pokémon Colosseum is a 3D role-playing game viewed from a third-person perspective.[2] The player, controlling a Pokémon Trainer named Wes (default name), moves through various towns and other locations (traversed using a type of one-wheeled motorcycle), battling enemy Trainers and completing quests. Items are purchased at "Pokémon Mart" locations using the game's currency, "Pokémon Dollars" (). When a battle starts, the screen switches to a turn-based interface where the player's and enemies' Pokémon fight. Most battles are of the "double battle" format, which means two Pokémon on each side at one time. However, each Trainer can carry up to six Pokémon at one time, so once a Pokémon is defeated, his or her Trainer must switch out another one unless no more are left. Battles are also conducted at "Colosseums" in several cities.[3]
Unlike most Pokémon games, Colosseum does not feature random encounters. The player begins the game with two Pokémon. More are obtained throughout the game by "Snagging" them from other Trainers using Poké Balls of various strengths. Only specifically designated "Shadow Pokémon", whose hearts have been artificially closed, can be Snagged.[2] Pokémon can be traded between Colosseum and the Game Boy Advance games Ruby, Sapphire, FireRed, LeafGreen and Emerald.
Each of the player's Shadow Pokémon has a purple gauge that is drained by battling and coming to like the player. Once a Pokémon's gauge is empty, the player may "Purify" the Pokémon by bringing him or her to Celebi's shrine in Agate Village, or by using a rare "Time Flute" item. Purifying Shadow Pokémon is desirable because while in that status, they will often disobey the player, they cannot gain experience points, and their moves are at first restricted to "Shadow Rush".[4] Additionally, Shadow Pokémon will sporadically enter "Hyper Mode" state during battle, causing them to disobey the player character or attack themselves until the condition is alleviated by selecting the "Call" battle command.[3]
Aside from the story mode, Colosseum also features several non-canonical battle modes. In the "Quick Battle" mode, the player can battle either CPU trainers or friends, using Pokémon obtained in the story mode or randomly assigned ones. Battles in this mode do not result in gain of experience points or money. In the single-player battle mode, the player competes at Colosseums—stadiums used throughout the game for Pokémon battles—and earns "Poké Coupons", another currency which can be used to buy rare items. In the "Gang Battle" mode, up to four players can compete in a tournament. The first can use Pokémon obtained in the story mode, or from the Game Boy Advance games. Players two through four, however, can only use Pokémon from the Game Boy Advance games.
