The Three Bears appeared in the episode "Goldilocks and the 7D". They were after Goldilocks because although she is adorable, she a freeloader. She always tricks the owners with her cuteness. Luckily, The Three Bears know what she is doing. They tried to warn others about Goldilocks, but since they are bears and thus get a bad rep in most fairy tales, nobody let them in. They're cuddly too.
They are all brown because of their fur.
In the show
In "Goldilocks and the 7D", they are seen chasing Goldilocks, for breaking into their house, ate their food, and busted all the toys. They keep finding Goldilocks until they got themselves a tea with Queen Delightful.