Is Teddy able to transform into a werewolf?

No, he is not a werewolf in any way.

I don't think there is any indication in the vitabu that a metamorphimagus could take a form of an animal completely. Not to mention a werewolf.

But even if a metamorphimagi could transform completely into an animal...Into a wolf, perhaps, but a werewolf is a completely different creature than a regular animal. It's not even comperable to hyppogrif and such magical animal.

So no, I really don't think he could transform into a werewolf. Not even in just the appearence.

J K Rowling has confirmed that Teddy didn't inherit being a werewolf from Lupin.