- 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!