- READY SET SLIME! Nickelodeon Kart Racers is back and we've brought the whole gang and MORE! In Nickelodeon Kart Racers 2: Grand Prix you can select from 30 playable characters and 70 companion characters to assemble your ultimate pit crew across your favorite Nickelodeon series including Jojo Siwa Spongebob Teenage Mutant Ninja Turtles Rugrats Hey Arnold! Ren & Stimpy The Loud House and more!