Here is the full list of all 19 FutureGrind trophies - there are 3 bronze, 7 silver, 8 gold and 1 platinum.
Earn 1 diamond trophy
Complete a track with the Gimbal bike
Complete a track with the Left Coast bike
Complete a track without spinning. At all. Don't touch the spin input. Seriously.
Complete a track with the Slice bike
Collect all other FutureGrind Trophies
Complete a track with the Xero bike
Complete a track with the Subverse bike
Complete an assignment from the hacker
Complete a track in the Luun region
Destroy the Device
Access an unauthorized area of memory
Destroy the P.R.A.X.I.S. system
Earn 10 diamond trophies
Earn 30 diamond trophies
Grind 42,195 meters
Spin your bikes for a total of 314,159 degrees
Complete a track without jumping. Good luck.
Score 250,000 points or more on a score attack