Here is the full list of all 30 Disgaea PC achievements.
Defeated all EX bosses!
Defeated the Extra Boss "Item God 2"
Obtained the Hyperdrive!
Dealt 10,000,000 Damage!
Defeated the Extra Boss "Baal"
Defeated the Extra Boss "Marjoly"
Defeated the Extra Boss "Priere"
Performed 10 transmigrations
Dealt 100,000 Damage!
Completed Final Episode of Etna Mode "Chronicles of Etnarnia"
Completed Ep. 1 of Etna Mode "Super Dimensional Etna"
Obtained Total LV 10,000
Cleared Extra Stages "Cave of Ordeal"
Obtained Total LV 5,000
Completed Final Episode "What Lies Beyond the Battle"
Obtained Total LV 1,000
Obtained 10,000,000 HL at the end of battle
Completed Ep. 10 "Angels, Demons, and Humans"
Defeated the Extra Boss "Item God"
Obtained Total LV 100
Defeated the Extra Boss "Item King"
Obtained 1,000,000 HL
Obtained the Dream Hand!
Completed Ep. 5 "Etna's Secret"
Performed your first transmigration
Killed 1,000 enemies!
Killed 500 enemies!
Completed Ep. 1 "Prince of the Netherworld"
Killed 100 enemies!
Defeated the Extra Boss "Item General"