"My Present to the Future"...the kid would grow up to become a famous astronomer and pave the way for interstellar travel, which would bring about a new era of world peace. Prime Evil didn't like that, so he tried to haunt the kid's telescope so that it would show ghosts instead of stars.
*remembers puzzle piece collection that forms a mountain*
I remember very little of that show. The ape was named Tracy, one of the human GhostBusters was named Eddie, and when they went to work, the went on this complicated trip that clothes and put their backpacks on then in a comical way that ends with all three of them dropped in the car. Their main weapons were a dematerializer, a weapon that shoots gum and one that shoots rope.