Platinum mode
Press X, B, L, R when "Press Start" appears at the title screen.
Flat mode
Press Down, Up, B, X when "Press Start" appears at the title screen.
Big heads
Press X, B, Up, Down when "Press Start" appears at the title screen.
Small heads
Press X, B, Down, Up when "Press Start" appears at the title screen.
All boxers
Win the Bronze, Silver, and Gold belts.
Mike Tyson Challenge
Defeat Mike Tyson and win the Gold belt to unlock the undisputed champ mode..
Fight as Mike Tyson
Win the Gold Belt to unlock Mike Tyson in single player mode.
Fight as Iron Mike
Win the Mike Tyson Challenge to unlock Iron Mike, the early version of Mike Tyson.