Here is the full list of all 22 DUCATI - there are 90th Anniversary achievements worth 1,000 gamerscore.
Win a race with Pro physics
Pull a stoppie for 2 seconds in any game mode
Reach at least the third place in all the events in the Historic Tour mode
Unlock all Titles
Unlock the "Great Victories" category in Historic Tour mode
Collect all the bikes in the game
Unlock the "Modern Era" category in Historic Tour mode
Reach a total of 30 bikes in your collection
Unlock the "2000s" category in Historic Tour mode
Reach a total of 20 bikes in your collection
Unlock the "90s" category in Historic Tour mode
Reach a total of 15 bikes in your collection
Unlock the "80s" category in Historic Tour mode
Reach a total of 10 bikes in your collection
Reach first place in an event in the Historic Tour mode
Unlock the "70s" category in Historic Tour mode
Reach a total of 5 bikes in your collection
Complete 20 multiplayer races
Complete 10 multiplayer races
Pull a continuous wheelie for 8 seconds in any game mode
Unlock a Title
Complete your first multiplayer race