Here is the full list of all 15 Blaze and the Monster Machines: Axle City Racers achievements.
Unlock all the STEM images
Finish the Adventure
Win the First 10 Races
Participate in Final Adventure
Win The third Championship
Win The second Championship
Win The first Championship
Step on a boost pad 30 times
Use special skill 10 times
Unlock the first STEM image
First Race Win
Win a race in split screen
Play a 4 player split screen race
Finish The Tutorial
Use a Special Skill for the first time