Here is the full list of all 27 Nickelodeon: Kart Racers achievements worth 1,000 gamerscore.
Unlock every upgrade in the store.
Win all Cups in Expert mode.
Activate the Slime in all the locations.
Win 9 victory laps.
Compete 10 times in each Arena mode.
Compete in the Arena for the first time.
Co-operative special attack for the first time.
Win all Cups in Normal mode.
Win a Cup in Expert mode.
Win with all racers.
Play as each racer at least once.
Use custom power ups for all the racers.
Take down at least 3 opponents in a single race.
Win a Cup in Normal mode.
Break 5 objects in a single race using boost.
Win all Cups in easy mode.
Put in the miles on the jetski.
Win at the last second in Grand Prix Mode.
Modify your kart for the first time.
Find a shortcut.
Win a Cup in easy mode.
Activate the Slime valve for the first time.
Win a victory lap.
Beat your record for first time.
Win your first race.
Use a custom power up for the first time.
Use boost for the first time.