Even if the VL does grip him, the health drain is slow, and werewolves have plenty of health. The werewolf summons will stun him with their lunge attack, and drop the player. Unless they're by a cliff, VL grip wont matter much. And for those who say that the VL can just summon the Gargoyles, they'll be quickly dropped, like this guy said, and the VL will be open for attack while he's gripping whoever. 3 against 1 after that, since the gargoyles are so weak.
On a side note, I'm glad to see I'm not the only one who fights Legendary dragons as a werewolf, since before everyone just kept calling me a liar, but I'm not so sure that a dragon can be stunned by the power attack. Does any1 else know or can they confirm this? If not, I'll try it out. I dont see why not since u can with shield bash or dual magic attacks though.
Yep the power swipe stuns the dragon just like the power shield bash, it's how I keep them on the ground

All hail the pack, all hail Lord Hircine
As far as I can tell it will depend on the person controlling the creture, they both could easily kill each other depending on who make a wrong move first.
Pretty much, an AI controlled VL or werewolf isn't going to stack up to a player controlled VL or werewolf.