Anyone who thinks Kabuto is giving Obito a fight because he can use Senjutsu should just stop. That's wank beyond wank right there.
-Obito stomps him no difficulty. Onmyoton tanks all his attacks and then it disintegrates him. Don't come here with that Senjutsu BS, cause it still tanks attacks pretty well. It took a near half Kurama sized Rasengan with Senjutsu in it to get past the Onmyoton shield. White Rage won't do anything as the way it damages doesn't use Senjutsu. Same goes for Muki Tensei and the rest of Kabuto's techs are too weak to make a difference. Not even gonna mention Bijuu Dama as its not necessary.
-Naruto wins. The only thing worth mentioning in Kabuto's arsenal that will do any damage to Naruto is Jinton, which can be easily dodged. Chakra Roar blows away White Rage and Bijuu Dama blows Kabuto off the face of the planet. This doesn't change in or out of a cave.
-Hashirama squashes him as well, in or outside of a cave.
-Edo or Alive Madara squashes him in or out of a cave as well.
-BM Minato nukes him.
Everyone else loses. Saying no one can beat him is overrating the living shit out of him.