Adidas Power Soccer '98 cheats and cheat codes for Playstation

Enable cheat mode
Hold L1 + L2 + R1 + R2 at the main start-up screen to bring up the
cheat entry screen. After that, press the following button combinations 
to enable different cheats:

Giant heads:
Press Square, Circle, Circle, X, Triangle, X, Square, Circle to 
unlock big heads.

Win match:
Press X, Triangle, Triangle, Circle, X, Square, Circle, Triangle. 
Then, pause the game to win the match.

Unlock bonus teams:
Press X, Triangle, X, Square, Circle, Square, X, Triangle. 
If the code is accepted, you will see a new flag at the 
right of The Netherlands.

Unlock "The Difference" stadium:
Press Square, Circle, Square, Triangle, Triangle, Circle, X, X to 
unlock secret stadium.

Watch the credits:
Press Circle, Square, Triangle, Circle, X, Triangle, Triangle, Square.