Here is the full list of all 51 Sonic Unleashed trophies - there are 35 bronze, 14 silver, 1 gold and 1 platinum.
This is the platinum trophy and is unlocked automatically when all the trophies have been unlocked
Cleared all Sonic the Werehog stages
Collected all Sun Medals
Collected all Moon Medals
Cleared all Sonic the Hedgehog stages
Talked to all townspeople
Cleared all hot dog stand missions in Empire City
Got every type of food
Gave all souvenirs to the Professor
Cleared all hot dog stand missions in Adabat
Cleared the Louie Montaine missions in Empire City and the Ana missions in Mazuri
Cleared all hot dog stand missions in Shamar
Reached the Goal of Arid Sands, Act 1 as Sonic within 2'50"
Cleared all hot dog stand missions in Chun-nan
Cleared all hot dog stand missions in Eggmanland
Cleared the game
Restored the sixth continent
Achieved an S Rank with Sonic the Hedgehog for the first time
Exorcised everyone
Restored the fifth continent
Achieved an S Rank with Sonic the Werehog for the first time
Collected half of the Moon Medals
Cleared the Marcantonio missions in Spagonia
Collected half of the Sun Medals
Cleared all hot dog stand missions in Holoska
Upgraded all of Sonic the Werehog's stats to their maximum levels
Completed all missions for a townsperson
Became best friends with Chip.
Cleared all hot dog stand missions in Spagonia
Have mastered the Lightspeed Dash technique
Upgraded all of Sonic the Hedgehog's stats to their maximum levels
Bought a product from Wentos
Restored the fourth continent
Achieved 10,000 total combos
Restored the third continent
Restored the second continent
Have mastered the Air Boost technique
Have mastered the Wall Jump technique
Have mastered the Stomp technique
Gave a souvenir to the Professor
Cleared all hot dog stand missions in Apotos
Have attained Combat Level 20
Have attained Combat Level 15
Reached the Goal of Windmill Isle, Act 2 as Sonic within 2'35"
Collected 5,000 total rings
Cleared all hot dog stand missions in Mazuri
Have attained Combat Level 10
Defeated 1,000 enemies
Restored the first continent
Have attained Combat Level 5
Cleared Act 1 of Tornado Defense without taking damage