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