In Toy Story he's first seen on Sid's workbench, along with the Pump Boy, Legs, and Ducky, retrieving parts of Janie and Pterodactyl. Initially thought to be a cannibal, the mutant toys later turned out to be friendly after they fixed Buzz and repaired the Janie Doll and the Pterodactyl.
Toy Story: The Video Game
Rockmobile appears in the later part of the level "Battle of the Mutant Toys" in Toy Story: The Video Game. He, along with Legs and Babyface will attack Woody and Buzz on Sid's workbench. Using Buzz's karate chop action, they're able to escape.