Unlimited ammunition:
Press B , X , B , Y , A , X , A (2) at the title screen.
Unlimited health:
Press A , B , A , Y (2), X , B , Y at the title screen. Once you or a CPU dies,
your/their health bar replenishes to the maximum.
All arenas:
Press Y , B , Y (2), A , X , B , X at the title screen.
All costumes:
Press B (2), A , X , B , Y , A , B at the title screen.
Play as Butch:
Successfully complete challenge mode as Tyke.
Play as Ducking:
Successfully complete challenge mode as Nibbles.
Play as Eagle:
Successfully complete challenge mode as Duckling.
Play as Lion:
Successfully complete challenge mode as Butch.
Play as Nibbles:
Successfully complete challenge mode as Spike.
Play as Spike:
Successfully complete challenge mode as Tom.
Play as Tyke:
Successfully complete challenge mode as Jerry.
Play as Monster Jerry in multi-player mode:
Successfully complete challenge mode as Lion.
Play as Robot Cat in multi-player mode:
Successfully complete challenge mode as Eagle.