Codex Gamicus

Pokémon Colosseum (ポケモンコロシアム, Pokemon Koroshiamu?) is the first GameCube incarnation of the Pokémon video game franchise. It incorporates elements of both the main handheld games in the series as well as the Pokémon Stadium games. The game was released in Japan on November 21, 2003, and was released in North America on March 23, 2004. It was released in Europe on May 7, 2004. It was released in Australia on June 24, 2004. It has since been followed up by Pokémon XD: Gale of Darkness, a 2005 sequel to this game.

Pokémon Colosseum puts significantly less importance on the non-RPG aspects of the game than Pokémon Stadium and Pokémon Stadium 2. For example, there are no minigames, nor is there a Gym Leader Castle/Tower. While it is the first 3D Pokémon video game with an RPG mode, it doesn't allow the player to use rental Pokémon the way the Pokémon Stadium games did. This was probably done because Pokémon are obtainable in the RPG mode, thus most of the features in the game are still usable without a Game Boy Advance Pokémon game or rentals. This title features support for Pokémon Ruby Version, Pokémon Sapphire Version, Pokémon Emerald Version, Pokémon FireRed Version and Pokémon LeafGreen Version video games.

A first in the Pokémon series, this game features a true 3D role-playing game mode that allows the player to capture Pokémon that could not be captured in the Ruby/Sapphire video games, allowing them to eventually be transferred into said games. This includes Legendary Pokémon such as Ho-Oh, Entei, Raikou and Suicune. It also adds a new Pokémon status, Shadow Pokémon, in which this game's plot revolves around. These Pokémon cannot be traded to any game until they lose their Shadow status, and are effectively forbidden from use outside the Story mode until purified.