Disgaea DS Cheats - Nintendo 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.

Unlock Etna's Secret Chamber
Press the button behind the throne, another one in the skull beside the weapon shop, and check the wall behind the Prinny in the same room as Longinus.

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.

Bonus characters
Complete the indicated task to unlock the corresponding character.

Adell - Complete the "Demon Hall Mirror" stage in the Cave of Ordeals six times.
Marjoly - Reach rank 9 in the Dark Assembly, pass the "Mysterious Seal" bill, and complete all the stages.
Plenair - Complete the game, talk to Plenair, then choose the blank option
Priere - Reach rank 8 in the Dark Assembly, pass the "Alternate Netherworld", bill, and complete all the stages.
Rozalin - Complete the "Demon Hall Mirror" stage in the Cave of Ordeals seven times.
Zetta - Pass all the enemy bills, get Gordon into your party, then complete the first stage in "Stellar Graveyard" again.

Prinny Commentary
Complete the game and start a new session using your cleared saved game file.

Alternate Endings
Complete the indicated task to unlock the corresponding ending.
Dark Assembly - Force proposals in the Dark Assembly fifty times.
Etna Heroine - Get at least 100 ally kills before Chapter 5, Stage 4, then kill Maderas when prompted.
Flonne Tragedy - Get at least 50 ally kills before Chapter 3, Stage 4, then kill Hoggmeiser when prompted.
Good/Best - Complete the game without any ally kills.
Item God - Kill an Item God or Item God 2.
Midboss - Lose to the mid-Boss of Chapter 1, 4, 6 or 10.
Normal - Have at least one ally kill and do not fulfill the requirements for any other ending.
Overthrowing Earth - Pass the "Human World" proposal at the Dark Assembly, then complete the Human World stages.

Complete the indicated task to unlock the corresponding ending in Etna mode:

Beauty Tyrant Overlord Etna - Pass the proposal for Alternate Netherworld and The Mysterious Seal in the Dark Assembly, then defeat Priere, Marjoly and finally Baal.
Normal - Complete the last chapter in Etna mode.

Adel and Rozelin
Use the following steps to get Adel and Rozelin from the second Disgaea on your team. First, complete the Cave Of Ordeals. When this is done the Demon Hall Mirror will be available. Do this level four or five times and you will have to fight Adel at level 2,000; then Adel at level 2,000 and Rozalin at level 2,500 at the same time. When they are defeated they will join your party. Demon Hall Mirror will also become a good leveling up location.

Defeating Item Gods
Once you go into the stage, look at the bonuses for invincibility geo spots. Use your characters to steal all those spots. Hopefully you will find an area to pin the Item God in, then just whittle his health down. You can use this method to kill the Item God 2 in the Aracadia. Depending on your team's level, you could be in for a long fight but you cannot lose.