Here is the full list of all 27 Scribblenauts: Showdown trophies - there are 8 bronze, 12 silver, 6 gold and 1 platinum.
Unlock all other trophies.
Make it to the finish line in Take Flight! with full health.
Score at least 1500 points in Drone Drop!
Win a game of Get Served! without losing any health.
Knock down a tower in 8 launches in Tower Topple!
Unlock all the custom Scribblenaut parts.
Create 100 Sandbox objects.
Unlock all custom Sandbox objects.
Unlock all vehicles in the game.
Create one of Maxwell's brothers in Sandbox Play or a Wordy game.
Unlock all 8 Sandbox levels.
Play Sandbox with two players.
Shutout a player in Versus by winning every single round.
Complete a 9 round Versus match.
Complete a 25 round Versus match.
Play every Speedy game at least once.
Earn 100 Starites.
Complete a 15 round Versus match.
Play every Wordy game at least once.
Win a game of Balancing Act! without dropping any of your objects.
Create a chain of 10 objects in Rocket Rubble!
Win 5 consecutive games against a single player.
Win a game of Super Sprint! without hitting an obstacle.
Complete a Showdown with 4 players.
Earn 25 Starites.
Create all 15 custom Scribblenauts.
Create a custom Scribblenaut.