The Colosseum is a fighting arena in Sonic Battle.
The Colosseum is an entirely virtual arena consisting of a pulsing green grid forming the ground, and the obstacles consisting of red wireframe blocks. These red blocks are see-through, which renders stealth tactics useless here, necessitating players to use more advanced strategies than in other arenas.
This arena typically has no relevance in Story Mode, but Emerl can visit Tails' Lab to participate in Virtual Training, where he will fight simulations of the game's other characters in each of the game's arenas, including this one. By winning matches in Virtual Training, Emerl will be rewarded with a Rare card, which can include his Ultimate Skills. All of Emerl's rounds in Challenge Mode also take place in this arena.