Here is the full list of all 21 Atari Flashback Classics Vol. 3 trophies - there are 4 bronze, 9 silver, 7 gold and 1 platinum.
Do 99 points of damage to the Imp
Clear an entire Rack in Pool Shark
Achieve a score of 300,000 or higher in Yars' Return
Get to the top of the local leaderboard in Maze Invaders
Try every game
Score 100 or more in Frog Pond
Earn all trophies
Get Extended Play in Fire Truck with two players
Get Extended Play in Monte Carlo at Medium setting
Reach a score of 20,000 or higher in Saboteur
Complete all 32 levels in Xari Arena
Get to round 10 in Holey Moley
Retrieve at least 6 treasures in Aquaventure
Clear the level in Canyon Bomber
Clear the level in Avalanche
Spell SKYDIVER
Shoot at least 15 objects in a row in Astroblast without any score penalties
Finish Adventure II without dying once
Score at least 65 before refuelling and at least 90 overall in Air Raiders
Achieve a Commander rating in Star Raiders
Beat the computer in Atari Baseball