Stronger Characters:
Beat the game with either character and save. Start the second game with the saved info. When the second game is beaten you can start a new game with your strength from your prevous game.

Infinite Platinum Coins:
At the main menu press X, X, X, X, X, Triangle, X, X, X, R2, R2, L1, L1 you hear a sound that confirm the code.

Catfight!:
After you get the dragon wings from Wylaf, in Rue's chapter, go to the Inn and save, (because' you'll want to see it again) now go in the Hotel. The lobby will be empty, so go up the stairs to see a VERY funny exchange of words (and blows) between Mint and Maya.

Retain HP & MP:
Beat the game with both characters and when you are asked if you want to save (after the credits) choose yes and then you will be able to get a sort of time trial adventure and you get to keep all the enemies that you killed in the last level, the armor you had last and your HP and your MP. You also hit as hard as you did when you beat the game. But with Rue, you don't get to transform into the monsters you had at the end of the game and I don't know what happens with claire though because I'm still playing Rues game.

Hobbes The Lush:
In the cave level, when you have to melt the block of ice as an animal (with Rue), get more MP, and melt the block of ice beyond the original one and get a rare wine.Sell it to Hobbes, and watch his prices drop.

Thanks to Revolution readers dono, Tim, Frosty, gismogurl65 and Nick Balsis!