Whacko Keeper
In any type of match, pause the game go the other team on controller select then go back to the match (you should now be the opposition). Give the ball to the team that isn't you. Press and hold L1 whilst the keeper is coming at you (still holding L1) press start then go back your team. Their keeper will now stay out for one half of the match.

Win a stadium
Win the championship club with a club and you will get a new stadium.

Seoul stadium
Win the International Cup to unlock the Seoul stadium.

Stade de France stadium
Win the Club Championship to unlock the Stade de France stadium.

Yokohama Stadium
Win the ECC Trophy to unlock the Yokohama Stadium.