Enter the following as your name at the "Create a Character" in Career mode to play as the following person...
MECCA - Ashy Knucks
MRBARRY - Barry Sanders
OSUNA - Bernando Osuna
HATCHER - Charles Hatcher
ZITO - Chuck Zito
BOSTICE - David Bostice
DEFIAGBN - David Defiagbon
DEMART - David DeMartini
JGIAMBI - Jason Giambi
BAILEY - Joe Mesi
JBOTTI - John Bottie
SBATISTE - Muhammad Ali
OWNOLAN - Owen Nolan
AUSTIN - Ray Austin
STEVEF - Steve Francis
NELSON - Trevor Nelson
Signature Moves
As do most people, they don't read the manual... To perform a boxer's signature move, press Trinagle Circle, in career mode, you must earn one after so many practice sessiosn
Bite opponent's ear
For some Tyson action, clench the opponent and press Triangle + Circle + X + Square
Illegal kick
When your fists just arent' enough press Triangle + Circle + X + Square.