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