Fight as Shrapp:
Highlight Psyclopps and quickly press [PK], [PP], [SK], [PP] at the character selection screen. The keyboard equivalent is J, I, L, I for player one.
Fight as Carnigore:
Highlight Master Pain and quickly press [SK], [PP], [PK] at the character selection screen. The keyboard equivalent is L, I ,J for player one.
Unlimited continues:
Quickly press [Up], [Down], [Up], [Down], [Up], [Down], [Left], [Right], [Left] at the character selection screen. The keyboard equivalent is W, S, W, S, W, S, A, D, A for player one.
Limb Boss:
Quickly press [Up] + [Left], [Up], [Down], [Down] + [Right] at the character selection screen. The keyboard equivalent is W + A, W, S, S + D for player one.
