Jumanji the movie featured one of the characters, a young boy named Peter, turning into a monkey. The animated series followed up on this by turning Peter into all sorts of things (that's the glory of animation--transformation scenes don't require an FX budget). No wonder TF fans like me were so fond of the show. The only problem was that it was hard to find and wasn't repeated very often. But now you can watch nearly every episode to your heart's content, thanks to a kind fellow on Youtube. His videos are here.
As for which to watch? Well, here's a little TF guide:
Ep.01: Peter turns into a monkey.
Ep. 02: Peter turns into a turtle.
Ep.03: Peter turns into a mask.
Ep.06: Peter turns into a toucan.
Ep.07: Peter turns into a statue.
Ep.08: Peter turns into a miniature replica of the hunter Van Pelt.
Ep.10: Peter turns into a boar.
Ep.12: Peter turns into a frog
Ep. 21: Peter turns into a skunk, and various townspeople turn into an elephant, rhino, bear, warthog, fox, lizard
Ep.29: Peter turns into a salamander.
Ep. 36: Peter undergoes age progression.
Enjoy!