Here is the full list of all 27 Nickelodeon Kart Racers 2: Grand Prix achievements.
Finish every race of a single cup with at least 10 Slime Tokens
Unlock every driver
Beat 15 ghosts in Time Trial mode
Complete all 42 challenges
Perform 500 drifts across any game mode
Collect 500 Slime Tokens in total
Discover 5 different shortcuts
Perform 25 jump boosts in a single race
Buy 5 different kart parts in the shop
Perform 25 Slime stunts in a single race
Finish 10 Arena games
Activate 100 Chief skills
Hit opponents 30 times with projectiles
Unlock 10 crew members
Begin a race with a boost
Unlock a chief for the first time
Get the first place in a cup
Unlock a driver for the first time
Complete your first race
Destroy a projectile with any item or Chief skill
Play with 10 different chiefs
Unlock all crew members
Complete 100 races across any game mode
Get 3 stars on every cup in all game speeds
Buy every item in the shop
Play with every Chief
Hit opponents 500 times with items