Super Smash Bros. Brawl/Bosses

Ancient Minister
He appears to be the main villain of the game but he could be a hidden ally.

Petey Piranha
Petey shows up within The Subspace Emissary. He carries two cages, one in each hand that contain Princess Zelda and Princess Peach. You only get to save one.

Rayquaza
Rayquaza appears in The Subspace Emissary's jungle section, when Diddy Kong finds Fox's ship crashed near a lake.