Cheat mode: [Submitted by:Luggs]
Left, Right, Left, Left, Right, Up, Down, R1, R1, R1, R1, R1, R2.

All boxers: Luggs]
Left, Left, Right, R2, Left, Right, Right, R1, R1, R2.

Start at final match: [Submitted by:Luggs]
R2, Down, Right, Up, Left, R1, R1, R1, R1, R1, R1, R2, R1, R1, R2.

All training: [Submitted by:Luggs]
Left, Down, Up, Down, Up, R1 (20),R2.

Fat boxers: [Submitted by:Luggs]
At the character selection screen, press Right(2), Up, Down, Right, R1(2), R2. If you entered the code correctly, you will hear a sound.

Skinny boxers: [Submitted by:Luggs]
At the character selection screen, press Right(2), Up, Down, Right, R1, R2. If you entered the code correctly, you will hear a sound.

Undead boxer: [Submitted by:Luggs]
At the character selection screen, press Left, Up, Right, Down, R1(2), R2. If you entered the code correctly, you will hear a sound.

Huge gloves:
At the character selection screen, press Left, Right, Up, Down, R1, R2. If you entered the code correctly, you will hear a sound.

Champion costumes :
Win the game in championship mode to unlock the champion costumes.

Freak E. Deke :
Successfully complete the game in arcade mode to unlock Freak E. Deke.

Michael Jackson :
Successfully complete the game in arcade mode Two times to unlock Michael Jackson.

Box as G.C. Thunder :
Successfully complete arcade mode Three times to unlock G.C. Thunder.

Wild "Stubby" Corley :
Successfully complete the game in arcade mode Four times to unlock Wild "Stubby" Corley.

Shaquille O'Neal :
Successfully complete the game in arcade mode Five times to unlock Shaquille O'Neal.
[Submitted by:SNailB8ter]

Box as Freedom Brock :
Successfully complete arcade mode Six times to unlock Freedom Brock.
[Submitted by:SNailB8ter]

Box as Rocket Samchay :
Successfully complete arcade mode seven times to unlock Rocket Samchay.
[Submitted by:SNailB8ter]

Box as Robox Rese-4 :
Successfully complete arcade mode eight times to unlock Robox Rese-4.
[Submitted by:SNailB8ter]

Box as Mr. President :
Successfully complete arcade mode nine times to unlock Mr. President (Bill Clinton).

Box as The First Lady :
Successfully complete 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.
[Submitted by:SNailB8ter]

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.
[Submitted by:SNailB8ter]

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 :
Successfully complete championship mode to unlock the champion costumes.
[Submitted by:SNailB8ter]