Big head mode:
Press Square, Circle, Circle, 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,
Triangle, Square.
Bonus stadium:
Press Square, Circle, Square, Triangle, Triangle,
Circle, X, X
Win match:
Press X, Triangle, Triangle, Circle, X, Square, Circle,
Triangle. Then, pause gameplay to win the match.
Stupid commentaries:
Press Triangle, Square, Circle, Square, X, X,
Square.
Thanks to Revolution readers Thuglife Member and Mark Northcott!