All Working Disgaea DS Cheats - DS

Etna Mode (Japanese version)
At Title Menu, put your cursor on New Game (Top Choice) and then press [X], [Y], [B], [X], [Y], [B], [A]. You should hear Etna's voice before it starts up.

Unlock Etna Mode via New Game +
You opt to do Etna Mode using New Game + feature! When you proceed with Etna Mode using New Game +, enemies will be made stronger in contrast to proceeding by inputting code and it'll also host one of the best levelling spot in the game!

Check out all her entries in her secret chamber before the last chapter and you'll be given the option to do Etna Mode in New Game +.

Unlock Pleinar
Simply lose to Mid-boss the first time you meet him. Then on your new clear file, complete the tutorial level and talk to Pleinar. A new option will appear below the usual assembly things. Choose that and she will join at level 1.

Extra Classes
How to obtain the hidden character classes in Disgaea DS:

Angel - Female Cleric, Knight and Archer all at level 100 or higher.
Archer - Level 3 or higher in Bow Weapon Mastery.
EDF Soldier - 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 each at level 10 or higher.
Prism Mage - Level a Star Mage to Level 35.
Prism Skull - Level a Star Skull to Level 35.
Rogue - Both Fighter and Warrior, Males or Females, each at level 5 or higher.
Ronin - Female Warrior and Female Fighter each at level 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.
Thief - Fighter and warrior both lvl 5.