Win a match at one of the corresponding venues in Career mode to unlock it:
Madison Square Garden
The Staples Center
Box as Ko Rey Mo
Defeat Ko Rey Mo in the light heavy division in Career mode to unlock him.
Win the indicated match in ESPN Classic Fights mode with the listed boxer to unlock the corresponding style:
Judge Jab: Defeat Joe Frazier with Muhammad Ali.
Lethal Uppercuts: Defeat anyone with Roberto Duran.
Sinister Cross: Defeat anyone with Roy Jones Jr.
Slickster: Defeat anyone with James Toney.
Textbook: Defeat anyone with Oscar De La Hoya.
Uptight, and Hard Straights: Defeat anyone with Winky Wright.
Burger King trainer:
Win the Burger King event in Career mode. Then at the trainer selection screen, press Down until the Burger King appears as a choice. He gives you Heart when you fight.
Easy wins in Career mode:
Go to the options menu and set Illegal Blows to Off. Then, go to the fight store and buy the illegal head punch called Elbow Shot. During a fight, use the Elbow Shot to counter attack each time your opponent throws a punch. Note: Make sure you use the Elbow Shot as a counter attack so that you can connect cleanly and powerfully on you opponent's head. You will see that the Elbow Shot inflicts a lot of damage to your opponent, and will KO him in a short period of time, or TKO because you inflicted so much damage to his eyes.