In case people don't know the code:
Shield invisibility code - Pause the game with Start, then press up, up, down, down, left, right, left, right, square, triangle, you should hear a sound (doing the code again makes the shield visible again). Even though you don't see the shield, it's still there and you can use it to deflect things. Put the code in again to make it appear.
Like posted above, this wil really help make your characters look nicer.