Fat boxer
At the character selection screen, press Right(2), Up, Down, Right, R(2), L. If you entered the code correctly, you will hear a sound.

Thin boxer
At the character selection screen, press Right(2), Up, Down, Right, R, L. If you entered the code correctly, you will hear a sound.

Undead boxer
At the character selection screen, press Left, Up, Right, Down, R(2), L. If you entered the code correctly, you will hear a sound.

Big gloves
At the character selection screen, press Left, Right, Up, Down, R, L. If you entered the code correctly, you will hear a sound.

Champion costumes
Successfully complete championship mode to unlock the champion costumes.

Unlock G. C. Thunder
Successfully complete the game in arcade mode three times to unlock G. C. Thunder.

Unlock Wild "Stubby" Corley
Successfully complete the game in arcade mode four times to unlock Wild "Stubby" Corley.

Unlock Freedom Brock
Successfully complete the game in arcade mode six times to unlock Freedom Brock.

Unlock Rocket Samchay
Successfully complete the game in arcade mode seven times to unlock Rocket Samchay.

Unlock Robox Rese-4
Successfully complete the game in arcade mode eight times to unlock Robox Rese-4.

Unlock Bill Clinton
Successfully complete the game in arcade mode nine times to unlock Bill Clinton.