Here is the full list of all 51 Disgaea 4: A Promise Unforgotten trophies - there are 42 bronze, 5 silver, 3 gold and 1 platinum.
Complete all other trophies. You have obtained all the trophies.
Watch all of the special skills.
Collect all items (excluding grades). Now aim for completing all the grades, too!
Unlock all Evil Symbols.
Defeat God (self-proclaimed) and watch the ending.
Watch Emizel's epilogue.
Watch Desco's epilogue.
Watch Fuka's epilogue.
Open all chests at the base from Episode 1 to Post-Game.
Watch Fenrich's epilogue.
Collect all of the Pirate Ship parts.
All ranks of all job and monster classes can be created through Character Creation.
Inflict 10,000,000,000 damage.
Defeat Pringer X: Roar in the Land of Carnage.
Visit the Land of Carnage.
Clear all of the X-Dimension maps.
Defeat Prinny Kurtis in the Post-Game and make him an ally.
Defeat Zetta in the Post-Game and make him an ally.
Give 50 bribes.
Enforce discipline 100 times.
Explode ten Prinnies in a row.
Increase an item up to LV 300.
Accidentally destroy Axel's statue in the Mystery Room.
Throw and capture an enemy character in the base panel.
Defeat Asagi in the Post-Game and make her an ally.
Defeat Laharl in the Post-Game and make him an ally.
Train an ally up to LV 9999.
Defeat 100 Pirate Crew members in the Item World.
Steal 10 Rare and/or Legendary items.
Defeat Etna in the Post-Game and make her an ally.
Inflict 100,000 damage.
Fight five battles with the "Classic" display option. Pixels still rock!
Defeat Raspberyl in the Post-Game and make her an ally.
Get over 100,000,000 HL.
Defeat Archangel Flonne in the Post-Game and make her an ally.
Max out the Rosen Queen Company customer level.
Persuade by force three times. Demons should always resort to violence!
Defeat Axel in the Post-Game and make him an ally.
Conduct your first Map Edit.
Open 100 treasure chests.
Conduct your first Reverse Pirating.
Clear the main game and unlock the Post-Game.
Watch Artina's epilogue.
Cancel 1,000 battle actions.
Clear up to Episode 7 in the main story.
Clear 30 floors in the Item World.
Clear up to Episode 3 in the main story.
Defeat an ally character.
Reincarnate for the first time.
Get a Game Over from having your party get defeated.
Watch the opening anime. Enjoy Disgaea 4!