Enter
Circle , X , X , Square , X , Triangle , Circle , X
In the cheat section to unlock all courts.
Enjoy!

This cheat will let you max out all of your skills. You don't use your money for anything but Skills and you don't need over $150,000 to max them all out but you still get it.

Go to Options at Main Menu and go to Cheats and enter:
O , Triangle , Square , Square , Triangle , O , X , O

Have Fun!