Unlockables - Extra Classes

Angel Female Cleric, Knight and Archer all at level 100 or higher.
Archer Level 3 or higher in Bow Weapon Mastery.

EDF Soilder Level 30 or higher Gun Weapon Mastery.

Galaxy Mage Level a Prism Mage to Level 50.
Galaxy Skull Level a Prism Skull to Level 50.

Knight Female Warrior and Female Mage each at level 10 or higher

Majin Male Warrior, Brawler, Ninja, Rogue and Scout all at level 200 or higher.

Ninja Male Fighter and Male Warrior with a total level of 10 or higher.

Prism Mage Level a Star Mage to Level 35.
Prism Skull Level a Skull Mage to Level 35.

Rogue Both Fighter and Warrior, Males or Females, each at level 5 or higher.
Ronin Female Warrior and Female Fighter with a total level of 10 or higher.

Scout 2 Fighters/Warriors, Males or Females, each at level 5 or higher.
Star Mage Get 1 Fire,Ice and Wind Mage and level all 3 of them to level 5.
Star Skull Get 1 Fire,Ice and Wind Skull and level all 3 of them to level 5.

Etna Mode - There is a hidden mode in Disgaea Portable called Etna mode. Normally you have to get this mode by going through the game and reading Etna's diary every chapter, but you can unlock it instantly by entering the following code during the title screen, with the pointer on "New Game." If you're successful, you'll hear Etna's voice.

Code Effect

Triangle, Square, X, Triangle Square, X, Circle Unlock Etna Mode (JP)
Triangle, Square, Circle, Triangle Square, Circle, X Unlock Etna Mode (US)