The
Petopia link Aethien provided shows all the pet families and the additional skills each can learn (besides growl, cower, cobra reflexes, etc. that all pets can learn).
For example,
Bears can learn Bite and Claw. Depending on the level of bear you tame, it may come with one skill, both skills, or none at all. There are a ton of pet families that have the Bite skill. You could tame any of them, learn the skill from that pet, and then train it to your bear.
Does that make sense?