Hmm, he does use Mokuton as well, wonder how that works though. Looks like it's mainly his right side that uses it. So either, Obito has some will left in there, and is using doujutsu, mokuton, high speed and that black liquid jinton-like thingy. Or, he's not using doujutsu at all, just pure speed, that black liquid thingy and mokuton. And that it's the juubi that uses mokuton because mokuton came from the juubi in the first place.
Not sure about all of this, I'd expect it to be more obvious if he was using doujutsu. I mean, why would he need to use any gravitational jutsu to pull Naruto and Sasuke to him? When they're only a few feet away from him anyway? I don't see that at all.