Kids Cartoon: The New 3 Stooges

The New 3 Stooges (1965), episode "The Abominable Snowman":

Green yeti like Popeye's!

"Hello. Would you play with me? I'm fun."

"Say, what are you anyway?" "Well, I dunno, I'm just a cartoon."

"I can be anything!"

The yeti then proceeds to turn into all kinds of random things: a penguin, a dancing bear, a Wild West villain, etc.

At the end, Larry transforms into the yeti, much to Moe's dismay.

Hulu has the episode.