Kartia ^{(PlayStation)}

Level 20 Characters

First, this code only works in the females story(to my knowledge). In
chapter 2 beat all the enemies so only Zakuro is left. Then corner him.
He will just keep creating phantom miles. Have one character keep
attacking the phantoms until they are at level 20. This is also good for
getting the secret phantom items. It is easier if you make a clear game
save from Toxas quest, so you can use the weapons.

Level 20 easy with Toxa

In chapter 7 (when you fight Cross) defeat all the Phantoms except the ones
near Cross. When all the other Phantoms are dead, start attacking the ones
near Cross, but don't kill Cross himself. Once you kill off enough
Phantoms, Cross will just keep on making them. Stand just near Cross's move
limit and wait there. When the he creates the Phantoms they will just move
up to attack you. Kill them off and continue waiting. Cross will do this
forever. Level all your people up to 20 and then kill Cross.