Here is the full list of all 20 Asphalt 9: Legends achievements.
Star Up 30 cars
Unlock 30 cars
Perform 50 Traffic Knockdowns
Reach Reputation Level 10
Drift 75,000 meters
Destroy 600 race objects
Perform 100 Upgrades
Upgrade Garage to Level 5
Win 25 Races in Career mode
Perform 240 seconds of Air Time
Perform 50 Barrel Rolls
Perform 25 360s
Perform 15 Nitro Shockwaves
Complete 1st Season in Career mode
Perform 15 Perfect Nitros
Perform 10 Knockdowns
Perform 5 Perfect Runs
Win the 1st race
Complete 40 Seasons in Career mode
Obtain 800 Career Flags