Here is the full list of all 10 Longboard Stunts and Tricks achievements.
Hit your rival 80 times during the race
Complete all stages
Complete the time-limited race on stage 5 in 38 sec or less
Unlock all longboards
Collect 20 speed boosters
Achieve level 5 with any character
Collide with 50 cars
Get off track 8 times
Cover the distance of 2000 m total
Complete the time-limited race on stage 1 in 55 sec or less