Here is the full list of all 46 MX vs. ATV: Alive trophies - there are 34 bronze, 8 silver, 3 gold and 1 platinum.
Win all Bronze, Silver and Gold Trophies
Reach Rider XP level 50, chasing records is all that is left
Achieve every level 1 Race Goal
Own a 3 star vehicle for each class
Ride for over 100 miles in Free Ride
Beat a friend's record in a Free Ride Challenge
Get at least a silver in all the Challenges in a Free Ride event
Win a race at every track
Earn a podium on each track
Finish at least one race at each track
Win a race with the James Stewart character
Defeat James Stewart in a race
Welcome to the big leagues, it's time to race James Stewart, Pro Rider XP level 25
Own a 3 star MX or ATV
Win the race and do a 360 over the finish line jump
Pull off 100 stunts
Save 100 wrecks using wreck avoidance
Almost Pro, Reach Rider XP level 18
Complete 50 overtakes using bar banging
Finish 50 races online
Win 35 races online
Reach Amateur Status at Rider XP Level 10
Almost Amateur, Reach Rider XP Level 6 and make a name for yourself
Earn a podium in an online event with assists turned off
Win a race after not leading until the last lap
Capture 3 holeshots in a row
Win 5 races in a row
Save 35 wrecks using wreck avoidance
Beat a rider with a higher Rider XP than you
Get the holeshot and win a race
Change your Rider Skills
Wreck 50 times
Pull a wheelie over 150 feet
Land a backflip
Hydroplane over 120 feet of water
Find the bonus vehicle in all of the Free Ride events
Win a Gold medal in a Free Ride Challenge
Earn a medal in a Free Ride Challenge
Complete 5 overtakes with bar banging in a race
Earn a podium 3 races in a row
Reach Rider XP Level 2 and meet James Stewart
Customize your vehicle or rider
Visit the MotoClub Depot
Capture a record lap time
Finish a race without going off track
Finish a race