Stubby Corley :
Win arcade mode 4 times and box as wild Stubby Corley.

Shaq O`neil :
win arcade mode 5 times and box as Shaq O`neil.

Freedom Brock :
win arcade mode 6 times and box as Freedom Brock.

Rocket Samchay :
win arcade mode 7 times and box as Rocket

Samchay.Robox Rese 4 :
win arcade mode 8 times and box as Robox Rese 4.

Bill Clinton :
finish arcade mode 9 times and box as Bill Clinton.

Hilary Clinton :
win arcade mode 10 times and get Hilary Clinton.

Unlock All Boxers
From the main menu, choose Arcade Mode. Then select one or two players. On the boxer select screen, press Left, Right, Left, Left, Right, Up, Down, R-Trigger, R-Trigger, R-Trigger, R-Trigger, R-Trigger, L-Trigger. A bell will sound and all characters will now be available.

Fat Mode :
For added fun; try one of this code on for "size". At the character select screen enter:
RIGHT, RIGHT UP, DOWN. RIGHT, R TRIGGER, R TRIGGER, L TRIGGER.

Huge Gloves Mode :
How many times have you told your self "I would have hit you if my gloves were bigger". Ok, maybe not too many times, but, here's a code that will do just that. At the character select screen enter:
LEFT, RIGHT, UP, DOWN, R TRIGGER, L TRIGGER.

Skinny Mode :
For added fun; try one of this code on for "size". At the character select screen enter:
RIGHT, RIGHT UP, DOWN. RIGHT, R TRIGGER, L TRIGGER.

Undead Boxers :
This is a fun code. At the character select screen enter:
LEFT, UP, RIGHT, DOWN, R TRIGGER, R TRIGGER, L TRIGGER.

Freak E Deke :
Win arcade mode once and box as Freak E Deke.

Michael Jackson :
win arcade mode 2 times and box as Michael Jackson.

GC Thunder :
win arcade mode 3 times times and box as GC Thunder.