Retro Teams:
This cheat is to unlock a certain nation team's all star team, I currently found this out for Argentina. Enter an International Cup mode and win it, simple as that, then you should get a screen telling you: "You can now use Always Argentina" (or whatever team you choose to enter the cup with.

Unlock all Cups and Players:
Get all cups and players in start screen press Up, Up, Up, Up, Up, R2, R2, L2, L2, R1, L1, Left, Down, Right, Up.