Beat arcade mode to unlock Freak E. Deke.

Fat boxers

While you are at the character selection screen, press Right(2), Up, Down, Right, R(2), L. If the code was entered in correctly, you will hear a sound.

Skinny boxers

While you are at the character selection screen, press Right(2), Up, Down, Right, R, L. If the code was entered in correctly, you will hear a sound.

Zombie boxers

While you are at the character selection screen, press Left, Up, Right, Down, R(2), L. If the code was entered in correctly, you will hear a sound.

Huge gloves

While you are at the character selection screen, press Left, Right, Up, Down, R, L. If the code was entered in correctly, you will hear a sound.

Box as Michael Jackson

Beat arcade mode two times to unlock Michael Jackson.

Box as G.C. Thunder

Beat arcade mode three times to unlock G.C. Thunder.

Box as Wild "Stubby" Corley

Beat arcade mode four times times to unlock Wild "Stubby" Corley. 

Box as Shaquille O'Neal

Beat arcade mode five times to unlock Shaquille O'Neal.

Box as Freedom Brock

Beat arcade mode six times to unlock Freedom Brock.

Box as Rocket Samchay

Beat arcade mode seven times to unlock Rocket Samchay.

Box as Robox Rese-4

Beat arcade mode eight times to unlock Robox Rese-4.

Box as Mr. President (Bill Clinton)

Beat arcade mode nine times to unlock Mr. President (Bill Clinton). 

Box as The First Lady (Hillary Clinton)

Beat arcade mode ten times to unlock The First Lady (Hillary Clinton). 

Hidden New Year's costume

Set the system date to January 1 to unlock a Baby New Year's costume for Joey T.

Hidden St. Patrick's Day costume

Set the system date to March 17 to unlock a leprechaun costume for the referee.

Hidden Valentine's Day costume

Set the system date to February 14 to unlock a lover's costume for Lulu Valentine.

Hidden Easter costume

Set the system date to April 23, 2001 to unlock a bunny costume for Mama Tua.

Hidden Independence Day costume

Set the system date to July 4 to unlock an Uncle Same costume for G.C. Thunder.

Hidden Halloween costume

Set the system date to October 31 to unlock a skeleton costume for J.R. Flurry.

Hidden Christmas costume

Set the system date to December 25 to unlock an elf costume for Selene Strike and a snowman costume for Rumble Man.

Champion costumes

Beat championship mode to unlock the champion costumes.