Small players:
Press Square, R2, Right, L2, L1.

Big heads:
Press Triangle(2), L2, L1(2).

Alternate clothes:
Press Circle, L2, Left, R2, Triangle.

Black/white mode:
Press Up, R1, L2, R1, R2.

Head as ball:
Press Left, L1(3), R2.

Topless:
Press Down, R2(3), Triangle.

Small heads:
Press R2, Down, L2, L1, Circle.

70's mode:
Press L1, R2, L2, Circle, R1.

Full attributes:
Use all available attribute points when editing a player. Save the team that was just changed, then return to the team selection screen. Select the same team to be edited, and you will have more attribute points to assign to a player. Repeat this until all players have full attributes.