Contender Codes -

Win bout:
Hold L1 + L2 + R1 + R2 and press X during a bout in road to world title or tournament mode. Press X again to display a loading screen instead of the game trivia. Press X again to win the current bout.

Main Event boxers in versus mode:
Create a new boxer in Main Event mode. Select, then immediately save a boxer to a memory card. Repeat this process to save a second Main Event boxer to the memory card. Then, begin a match two player versus mode. Press Square at the character selection screen to choose one of the previously saved Main Event boxers.

Hidden exhibition mode boxers:
Win the World Championship and save the game. Press Square at the exhibition mode character selection screen, then press Square again to select Jackel, Goober, Rascal, and Beastman.

Two player mode boxing trainer:
Press Square at the two player mode character selection screen, then press Square again to select the boxing trainer.

Custom newspaper photo:
Note: This trick requires a dual analog controller. Begin a match in main event mode. Press L3 or R3 to take a snapshot of the current scene. The photo that was snapped will appear in the newspaper at the end of the bout.