The Colosseum is set in a grassy patch. It is decorated with Ferris Wheels and fountains in the surrounding area, and the audience is able to watch from both sidelines and from various tree houses surrounding the area.
When first challenged, the Colosseum simply features standard Double Battles against seven Trainers. After beating the game, the Colosseum hosts Little Battles, an upgraded form of Stadium 2's Little Cup. The only Pokémon allowed to participate must be at or below level five, and be in their first forms (including Baby Pokémon forms). Pokémon competing in Little Battles do not have to be hatched from an Egg, contrary to popular belief.