Highlight the "My Corner" option at the main menu, then press Left(3), Right(3), Left, Right(2). A sound will confirm correct code entry.
Big head mode
Highlight the "Fight Now" option at the main menu, then press Left, Right, Left, Right, Left, Right, Left. A sound will confirm correct code entry. Select the "Fight Now" option to have a big headed boxer.
Fight as Big Tigger
To unlock Big Tigger as a boxer, go to the main menu. Select "My Corner", then "Record Books", then "Most Wins-Boxer". Tap Up(2) and you will now be able to play as Big Tigger as a middleweight fighter. A sound will confirm correct code entry.
Alternate uppercut
Press Jab + Hook to throw an uppercut without Total Control Punching.
Recover from knockdown
Use the Left Analog-stick and Right Analog-stick to merge the images in your view until they become one.
Small Fighter
Highlight "Play Now" option at the main menu, then press Left(3), Right(3), Left, A. A sound will confirm correct code entry. Alternately, press Left, Right, Left, Right, Left at the main menu.
Various Punches
Bolo Punch special punch: Defeat Ray Leonard in career mode.
Ducking Hook special punch: Defeat Muhammad Ali in career mode.
Look Ma No Hands special punch: Defeat Roy Jones Jr in career mode.
Lunging Hook special punch: Defeat Chris Byrd in career mode.
Lunging Hook special punch: Defeat Evander Holyfield in career mode.
Sledgehammer special punch: Defeat Sonny Liston in career mode.
The Birdie special punch: Defeat Bernard Hopkins in career mode.
Get away with head butts or low blows
When the bell rings at the end of the of the round, use the illegal hit. As long as the bell to end the round sounds, you will not be disqualified.
Heavy bag training to increase punch power and speed
In the heavy bag training in career mode, start by a throwing a right hook to get the bag going, then throw a left hook while the bag is moving to the right. When the bag moves left, throw a right hook, etc. The bag will swing more and more, and you will receive the swing bonuses, increasing your score. Use good timing, and hit the bag when it is just entering the upswing. You will get more attribute points to increase your fighter's punch power and speed.
Longer Count
When your opponent's health is at 0 and he is about to fall down, hit him two or three times. The count will be longer.
Taunt
Press L + R + click Left-Analog-stick + click Right Analog-stick during a fight to taunt your opponent, regardless of controller configuration.
Get Tito trunks
Defeat Felix Trinidad in career mode.
Get Executioner trunks
Defeat Bernard Hopkins in career mode.
Get Wave In special punch
Defeat Felix Trinidad in career mode.
Get Watch The Birdie special punch
Defeat Bernard Hopkins in career mode.
Get Sledgehammer special punch
Defeat Sonny Liston in career mode.
Get Shine The Glove special punch
Defeat Jake LaMotta in career mode.
Get Lunging Uppercut special punch
Defeat Sugar Shane Mosely in career mode.
Get Lunging Hook special punch
Defeat Chris Byrd, Evander Holyfield, or Joe Frazier in career mode.