Here is the full list of all 51 Disgaea 3: Absence of Justice (EU) trophies - there are 42 bronze, 5 silver, 3 gold and 1 platinum.
Get all other trophies.
Get a Trophy from a Trophy Shop on the 90th floor.
Defeat the Baal Pirates in the Item World.
Defeat the 10 Gents Pirates in the Item World.
Defeat the Boney Pirates in the Item World.
Defeat the Prinny Pirates in the Item World.
Steal from all the Innocents and treasure boxes while Reverse Pirating.
Steal from all the Innocents while Reverse Pirating.
Get all the Reverse Pirating treasure boxes.
Do over 10,000,000,000 damage.
Defeat an enemy with 10 combos or more.
Clear Geo Blocks with 10 color changes in a row.
Defeat an enemy with a 10 story tower.
Receive 9 times and move over 60 panels.
Receive 4 times and move over 20 panels.
Magichange 5 times in a battle.
Capture an enemy during battle.
Accomplish over 255 combos in battle.
Counter Attack over 10 times.
Beat floors 1 to 100 in a Land of Carnage Item World without exiting.
Defeat the Kit Cat Pirates in the Item World.
Defeat the Garden Pirates in the Item World.
Defeat the Cheerates in the Item World.
Do over 100,000,000 damage.
Defeat the Red Pirates in the Item World.
Find Axel in the Item World.
Defeat the Shinsengumi in the Item World.
Defeat the Sports Pirates in the Item World.
Defeat the Pirate Club in the Item World.
Defeat the Pirate Cleaners in the Item World.
Talk to the Cat God at the top of the Treasure Tower.
Beat floors 1 to 100 in an Item World without exiting.
Defeat the Element Pirates in the Item World.
Defeat Wise Innocents in the Item World.
Defeat the Horizon Pirates in the Item World.
Defeat the UFO Pirates(?) in the Item World.
Defeat Eryngi Pirates in the Item World.
Defeat the Ghost Pirates in the Item World.
Defeat the Asian Pirates in the Item World.
Defeat UFO? in the Item World.
Defeat Donnax2 Pirates in the Item World.
Defeat Lucky Pirates in the Item World.
Defeat Z Pirates in the Item World.
Defeat the Cowboy Pirates in the Item World.
Do over 1,000,000 damage.
Get all the treasure boxes in the Treasure Room in the Item World.
Force the Student Council to approve your Home Room request.
Jump inside Evil Academy 100 times.
Play for over 10 hours without stopping.
Clear Geo Panels with 5 color changes in a row.
Get hit by ABC Gum.