This is Football Cheats
PS1 | Submitted by Soccer guyUnlimited Energy
Go to where you edit the player's attributes and use up all of the energy that you got left. After that, save the team that you customized, and go back to where you select your team that you want to customized, select the same team that you did the energy with, go back to where you edit the player's attributes and you should have more energy left. Do this cheat 5-7 times per person to have all players invincible.
PS1 | Submitted by GamesRadarVarious Cheats
Big Heads Triangle, Triangle, L2, L1, L1
BW Mode Up, R1, L2, R1, R2
A Head for Ball Left, L1, L1, L1, R2
Tiny Players Square, R2, Right, L2, L1
No Shirts Down, R2, R2, R2, Triangle
New Uniforms Circle, L2, Left, R2, Triangle
70's Mode L1, R2, L2, Circle, R1
Tiny Heads R2, Down, L2, L1, Circle
PS1 | Submitted by REJ100% overall team
Select the team you want to have a 100% overall. Make all players as good as possible, then go back to the main menu, and start playing a match with your team. After you won (or lose) the match, go back to customize team. Now you can make all your players better, and end up with a 100% overall.