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