If you want to make a perfect player (100 overall) go to create player mode and type in the name "Jim Jung" if you spell his name correct your player will be full on everything. As soon as you put in "Jim Jung" you can change the name to what ever you want and he will remain 100 overall.
At any of the Team Select Screen, press L, R or R, L to have a random selection given to you.
Enter the following names as shown for secret players.
grEEn jeLLo (case sensitive)
Joe Seeders Todd Dowd
If someone is injured, press C-Left, C-Left, C-Right, C-Right at the trainer's room. You can now take out an injured person for free.