File:Groudon.jpg
Groudon being unleashed in Pokémon Colosseum.
Pokémon Colosseum is a confirmed stage for SSBB. It appears relatively unchanged from Pokémon Stadium, save for a major graphical upgrade to the background.
Note that the stage currently has no official name, but Pokémon Colosseum is usually used by fans to differentiate between this stage and Pokémon Stadium.