Robot

Robot is a blue educational robot toy and Snake is a green-purple jointed rattlesnake toy that both appear in the Toy Story series. The two of them are always seen together (with Robot dragging Snake around) so it's assumed that they're friends. Robot is the only one of the two toys that can talk. The inside of Robot's head also lights up in different colors.

Toy Story
Snake is seen lifting weights during the song "Strange Things" while Buzz uses Robot's feet as a treadmill, and then right afterwards they assist him in trying to repair the spaceship box that he came in. Woody's job for them in the film was "Podium Duty".

Toy Story 2
They were also seen in Toy Story 2 when Buster comes into Andy's room, and later they're seen watching Mr. Potato Head's re-enactment of Woody's kidnapping.

Trivia

 * Robot has some notable similarities to WALL•E, particularly his robotic arms and treads.