Phantom Island: Extra Money:
You can find money around Phantom Island by jumping on certain places. You can find 100 Bordeaux by jumping in the stone circle in front of the house. There is also some behind the house at the bottom of the cliff in the water. There is also some on the roof of your house. Also, on the big tree next to the house you can find a book called the 'Changebook'. It is a very strong book for magic users. It is located on the edge where you can jump on to from your house'

Phantom Island: Kill Your Own Teammates:
Walk up to your teammate and press R2 to attack them. Press Toward + R2 to grab and throw them. This is useful for easy experience.

Bonus Characters:
Baal: Complete Extra Map 9
Etna: Complete Extra Map 2
Flonne (Fallen Angel form): Complete Extra Map 2
Laharl: Complete Extra Map 4
Mid-Boss: Complete Extra Map 5
Myao: Complete Extra Map 8

Bonus Maps:
Extra Map 1: Successfully complete the game
Extra Map 2: Complete Extra Map 1
Extra Map 3: Complete Extra Map 2
Extra Map 4: Complete Extra Map 3
Extra Map 5: Complete Extra Map 4
Extra Map 6: Complete a random dungeon with over 30 floors and enemies over level 300 on the bottom floor.
Extra Map 7: Complete Extra Map 1 through 6
Extra Map 8: Unlock Extra Map 6 and also complete a random dungeon with over 50 floors, and enemies over level 500 on the bottom floor.
Extra Map 9: Unlock Extra Map 6 and 8 and also complete a random dungeon with 99 floors, and enemies over level 1000 on the bottom floor.
Extra Map 10: Complete Extra Map 9

Extra Map 1:
Beat the game.

Extra Map 10 and Baal:
Beat Extra Map 9.

Extra Map 2:
Beat Extra Map 1.

Extra Map 3, Etna, and Flonne (Fallen Angel form):
Beat Extra Map 2.

Extra Map 4:
Beat Extra Map 3.

Extra Map 7:
Beat Extra Maps 1-6.

Extra Map 8:
Clear a random dungeon with 50+ floors, with Level 500+ enemies on the bottom floor, and have unlocked Extra Map 6.

Extra Map 5 and Laharl:
Beat Extra Map 4.

Extra Map 9:
Clear a random dungeon with 99 floors, with Level 1000+ enemies on the bottom floor, and have unlocked Extra Maps 6 and 8.

Mid-Boss:
Beat Extra Map 5.

Myao:
Beat Extra Map 8.

Pringer-X:
Complete the game and clear all the extra levels.

Extra Map 6:
Clear a random dungeon with 30+ floors, with Level 300+ enemies on the bottom floor.