Complete the following tasks to unlock the corresponding playable character in Versus mode.

Chao:
Beat ALL of Tails' levels with an 'A' rank.

Amy:
Beat ALL of Sonic's levels with an 'A' rank.

Big:
Get A ranks on ALL of Eggman's stage.

Chaos 0:
Beat ALL of Rouge's levels with an 'A' rank.

Mecha Sonic:
Beat ALL of Shadow's levels with an 'A' rank.

Tikal:
Beat ALL of Knuckles' levels with an 'A' rank.