Play as Gargos
     At the Character Select screen, press Z, A, R, Z, A, B.

Multi-Colored Characters
     At the Character Select screen, press Z, B, A, Z, A, L.

Reach the Sky Level
     At  the Character Select screen and in Two-Player mode, hold Down
on the analog stick + Kick.

View Credits
     Press Z, L, A, Z, A, R.

All Options
     Press Z, B, A, L, A, Z.