To unlock this stage, you must complete the "The Original Heavyweights" event.
Normal Form
This stage is a stationary, floating platform with smaller platforms above it. The two small platforms in the middle rotate. There's also a barrel that moves from side to side and can shoot you up managed to fall into it. The stage has no active hazards and screen transitions.
Omega Form
The battle takes place in single platform with no hazards or transitions.