So once I killed the two men outside of Snowclad Ruins, I dead thralled both of their bodies hoping they would use their transformation abilities in combat to aid me in my battles. They did not seem to transform at all though. I was wondering if anyone else has done this? If so did the thralled werebears transform to help you in combat?

No.

Werewolves do transform, after fast travelling the werewolf pack that sells you the rings attacked me and I killed them before giving them time to transform. In their human form they can be thralled, so to try I punched the thrall four times to make it go hostile against me and he began transforming (btw he stopped being hostile) so now I have an undead werewolf thrall.

They don't seem to ever transform back and *I think* they are a little buggy if there are two WW thralls (I'll have to investigate) but at least one is fully functional (I tried entering in battle and the WW attacked perfectly) and fast travel works very well.

So it seems that they only transform against the PC, the solution is to attack them (the best is to punch them) so they will transform and reset the hostility. One thing though, don't let them die because in their wolf form they can't be rethralled.

I'll try to thrall a werebear.

Now talk about a bad day for the enemies, attacked by a unique Daragonborn Vampire Lord, another VL (I know Serana doesn't transform but she is one) , two Werecreatures and a mage (Brelyna) with her Frost Atronach.

It would be easier to just summon them. You can get the summon from the Beast Stone.

It's a 60 second summon, and tedious to always be going to the Earth Stone to reacquire the power.