In one player mode when you battle in a new stage press start then quit and go to versus or any other modes.(except 1player mode) Then, pick any character and you will see that the last stage you were fighting in is available press X quickly or it will erase.
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.
Secret courses
On tournament or quick game modes, go to team battle and place players one, two, and three on team "A" and player four on team "B". Choose these players. First Spike, then Tom, then two Jerrys. You will now have access to the Some Like it Hotter and Raging Mouse courses. If you want to play these again, repeat the steps. Note: All players have to be human (four controllers used).
Note: This requires two controllers. To the secret levels (Some Like It Hotter and Raging Mouse), you must choose Tom for player one and Tom for player two. Turn off the other players. Note: Both players must be human. To get the levels again, repeat this.
Secret weapons
The following is a list of all the secret weapons and their effects. The weapons listed can only be found by destroying the playing field. The message "Map Destroyed" will appear when you have destroyed everything that can be broken. Note: In the two secret stages, "Some Like It Hotter" and "The Raging Mouse", fields can not be destroyed, thus there are no secret weapons for them.
That Sinking Feeling: Octopus (if thrown hard, causes other player to petrify).
A Fridge Too Far: Rotten Eggs (poisons player when thrown)
Haunted Mouse: Pirate Sword (stabs player).
Liao Meow: Bee's Nest (stuns player when thrown).
Franken Mouse: Electric Bomb (shocks player when thrown).
Towering Inferno: Time Bomb (10 seconds to throw at other player;explodes on impact).
Paws: Electric Eel (shocks player when stabbed).
Luncheons And Dragons: Excalibur Sword (knocks player unconsousn when stabbed).
Snow Fight: Ice Barrel (freezes player when thrown)
Scrap Yard Scrap Up: Hammer (knock player unconscious in one hit).
Unfurgiven: Branding Star (Burns player to a crisp when stabbed).
On Luncheons And Dragons, hit anything that can be destroyed. When it says "Map destroyed", look for the sword in the rock to find the secret weapon. The same can be done on all levels for different weapons. Note: If you use Jerry, Nibbles. or Tom, you may get a costume on Lungens And Dragons. On the western level, you can unlock a costume with Tom, Nibbles, and Spike.