All boxers:
Select the "Cheat" option at the "Setup" menu. Then, press Start, A, Y, X(2), Z(2), X, Y, A, Start.

Invincibility:
Select the "Cheat" option at the "Setup" menu. Then, press Start, A(2), Y(2), Z(2), X(2), Start. Note: This code can be enabled on controller one for player one or controller two for player two.

Turbo mode:
Select the "Cheat" option at the "Setup" menu. Then, press Start, Z(10), Start.

Constant power-ups:
Select the "Cheat" option at the "Setup" menu. Then, press Start, A, Y, A, Y, A, Y, X(3), Start. Note: This code can be enabled on controller one for player one or controller two for player two.

Conversation mode:
Select the "Cheat" option at the "Setup" menu. Then, press Start, Z, A, Y, X, Z(3), Start.

Intercontinental Tournament:
Select the "Cheat" option at the "Setup" menu. Then, press Start, A(3), Y(3), X(3), Start. Alternately, win all five default tournaments to unlock the Intercontinental Tournament.

Alternate costumes:
Select the "Cheat" option at the "Setup" menu. Then, press Start, A, Z, Y, X, Start. Alternately, successfully complete Life mode with a boxer to unlock a new costume for that character.

All boxers' Life mode:
Select the "Cheat" option at the "Setup" menu. Then, press Start, A, X, Y, Z, A, X, Y, Z, Start.

Scrap Yard arena:
Select the "Cheat" option at the "Setup" menu. Then, press Start, Y, Z, Y, Z, A(2), Start. Alternately, win all survival modes to unlock the Scrapyard arena.

Fight as King Khan:
Win the Top Contender Tournament.

Fight as Matador:
Win the Intercontinental Tournament.

Fight as Odiva:
Win the Pro Tournament.

Fight as Old Master:
Win the World Championship Tournament.

Fight as Training Robot:
Successfully complete training mode.

Hint: Restore energy:
Rapidly press A repeatedly after getting knocked down to restore a small amount of energy and help prevent a knockout.