Hold L1 + L2 + R1 + R2 at the main start-up screen to display the cheat entry screen. Then, enter one of the following codes to activate the corresponding cheat function.
Big head mode
Press Square, Circle(2), X, Triangle, X, Square, Circle.
Hidden teams
Press X, Triangle, X, Square, Circle, Square, X, Triangle. A new flag will appear to the right of The Netherlands.
View credits
Press Circle, Square, Triangle, Circle, X, Triangle(2), Square.
Bonus stadium
Press Square, Circle, Square, Triangle(2), Circle, X(2) to enable "The Difference" stadium.
Win match
Press X, Triangle(2), Circle, X, Square, Circle, Triangle. Then, pause game play to win the match of your choice.