Arsenal creation:
Always have at least eight to nine Auras in your arsenal, or else you will be lacking in Aura at the beginning of the mission and waste skills. Also, have a balance between long, medium, and short range attacks. Have perhaps three long range, four medium, and three short attacks. Make sure you are equipped with enough defense skills, especially low cost skills that you can use to block attacks that do not cause damage (such as Erase Skills). Finally, make one of your two classes the Nature class so that you can use healing skills like Healing Water.
New starting skills
At the beginning of a duel either in multi-player or scenario mode, as the timer is counting down if the skills you have in your arsenal are bad or you do not have any Aura Particles to start with, press Back before the timer reaches zero. You will reshuffle your starting skills. This can only be done once per duel, but it is a good way to avoid a bad situation. Additionally, for every thirty Xbox Live wins, you will be given one of forty Xbox Live skills.
Unlock FMV Viewer
In order to be able to view all of the FMVs in the game, you first need to be on Chapter 4. Towards the end of the chapter, you can get a mission from Mikan in the Clinic where you need to get some medication. After you successfully finish the mission, you'll be able to view all FMVs by talking to Mikan from that point and onward.
Necronomicon mistake
The environmental skill Necronomicon states that everyone's attack skills lose all bonuses, restrictions, and penalties. This is incorrect. Necronomicon actually only makes everyone's attack skills lose all bonuses.
Play as Monsters in multi-player
On the character select screen in versus mode you can play a monster instead of espers by hold both trigger down when you select a character. The portrait won't change but your in-game avatar will.
Xbox Live skills
Every 30 wins you aqcuire on Xbox Live will earn you one of 74 Xbox Live skills.
