At the character selection screen, hold L and press A, A, A, A, A, C-Up, C-Down, C-Left, C-Left, B, A, C-Right. The computer will now play the character for you.
At the character select screen, press and hold the L button while inputing the following code: C-up, C-down, C-left, C-right, B, A If done correctly, you will hear a beep. Now move the cursor over one of the question marks in the lower corners and press the R button. High Five appears! It's Dr. Kiln's right hand that was removed from his evil body! This character is powerful.
On the character select screen, hold Z or L and Press B, B, C-Right, C-Right, C-Left, C-Left, then press R on the "?" box to play Boogerman.
Hold Z or L and press B, C-left , C-up , C-right , C-down , C-up. You will now hear a sound. Then press R on the "?" box to play Earthworm Jim.
At the character selection screen, hold L and press A, B, A, B, A, B, C-Left, C-Right, C-Up, C-Right, C-Left, C-Right. Now you can pick any characters and see all the stages from a bird's-eye view.