Here is the full list of all 8 Looney Tunes Galactic Sports trophies - there are 4 bronze, 2 silver and 2 gold.
Buy all the gadgets in the ACME Shop.
Complete all of Marvin’s Quests.
Complete your first Marvin’s Quest.
Complete the Galactic Games mode.
Unlock all the characters.
Win your first Tournament in the Galactic Games.
Complete your first competition in the Multiplayer mode.
Buy your first gadget in the ACME Shop.