Box as Freak E. Deke
Successfully complete arcade mode to unlock Freak E. Deke.
Box as Michael Jackson
Successfully complete arcade mode two times to unlock Michael Jackson.
Box as G.C. Thunder
Successfully complete arcade mode three times to unlock G.C. Thunder.
Box as Wild "Stubby" Corley
Successfully complete arcade mode four times times to unlock Wild "Stubby" Corley.
Box as Shaquille O'Neal
Successfully complete arcade mode five times to unlock Shaquille O'Neal.
Box as Freedom Brock
Successfully complete arcade mode six times to unlock Freedom Brock.
Champion costumes
Successfully complete championship mode to unlock the champion costumes.
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 Sam 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.
Zombie Mode
At the character select screen press Left, Up, Right, Down, R1, R1, R2. You will hear a bell if entered correctly.
Big Gloves Mode
At the character select screen press Left, Right, Up, Down, R1, R2. You will hear a bell if entered correctly.
Chubby Mode
At the character select screen press Right, Right, Up, Down, Right, R1, R1, R2. You will hear a bell if entered correctly.
Toothpick Mode
At the character select screen press Right, Right, Up, Down, Right, R1, R2. You will hear a bell if entered correctly.
Unlock All Characters
At the Character select screen press:
LEFT, LEFT, RIGHT, R2, LEFT, RIGHT, RIGHT, R1, R1, R2
All characters will be unlocked. The question mark in the lower-right corner is the "Random fighter" button. Before you press X to confirm the fighter you want you can press the SQUARE button to change their costumes. You will have access to every costume, including the Holiday outfits. Not every boxer has a Holiday Outfit.
Note: This code also works in Championship mode.