Enter world mode, select "New Career" and choose any boxer, then enter "CLUBFUD" as a name and press Triangle.

Unlock John L. Sullivan and Docks stadium

Enter world mode, select "New Career" and choose any boxer, then enter "OLD MAN" as a name and press Triangle.

Boxer's heads grow when punched

Enter world mode, select "New Career" and choose any boxer, then enter "OUCH" as a name and press Triangle.

Boxer's heads spin when punched

Enter world mode, select "New Career" and choose any boxer, then enter "HURTS" as a name and press Triangle.

Boxer's necks stretch when punched

Enter world mode, select "New Career" and choose any boxer, then enter "NECK" as a name and press Triangle.

Invisible boxer

Enter world mode, select "New Career" and choose any boxer, then enter "GONE" as a name and press Triangle.

Small heads

Enter world mode, select "New Career" and choose any boxer, then enter "BINGY" as a name and press Triangle.

Big heads

Enter world mode, select "New Career" and choose any boxer, then enter "BONGY" as a name and press Triangle.

Big hands and feet

Enter world mode, select "New Career" and choose any boxer, then enter "STUPID" as a name and press Triangle.

Disable all cheats

Enter world mode, select "New Career" and choose any boxer, then enter "NORMAL" as a name and press Triangle.