Here is the full list of all 31 Disgaea 1 Complete trophies - there are 16 bronze, 9 silver, 5 gold and 1 platinum.
Performed 10 transmigrations
Defeated all EX bosses!
Obtained the Hyperdrive!
Defeated the Extra Boss "Item God 2"
Defeated the Extra Boss "Item God"
Defeated the Extra Boss "Baal"
Defeated the Extra Boss "Priere"
Defeated the Extra Boss "Marjoly"
Obtained Total LV 10,000
Obtained Total LV 5,000
Dealt 100,000 Damage!
Obtained Total LV 1,000
Cleared Extra Stages "Cave of Ordeal"
Obtained the Dream Hand!
Obtained 10,000,000 HL at the end of battle
Defeated the Extra Boss "Item King"
Completed Final Episode "What Lies Beyond the Battle"
Completed Ep. 10 "Angels, Demons, and Humans"
Performed your first transmigration
Obtained Total LV 100
Obtained 1,000,000 HL
Killed 1,000 enemies!
Completed Ep. 5 "Etna's Secret"
Killed 500 enemies!
Defeated the Extra Boss "Item General"
Completed Ep.1 "Prince of the Netherworld".
Killed 100 enemies!
Obtain all trophies.
Completed Ep. 1 of Etna Mode "Super Dimensional Etna"
Completed Final Episode of Etna Mode "Chronicles of Etnarnia"
Dealt 10,000,000 Damage!