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