Eight gates guy would wreck Juubito but can't seal him or remove the beasts from him, seeing as the juubi's jin has considerable regeneration feats. Naruto and Sasuke combined would wreck him for sure, but separately, just no, Obito wasn't even trying to fight them, most of the time, it was just them attacking and him showing them how meaningless their attacks were. Obito with a straight focused mind would wreck Naruto or Sasuke. Double MS Obito at full capacity would try, but Juubito knows all of kamui's loop holes, he may stand a chance, but just NO. Double Rinnegan + senjutsu madara would put up a nice battle with him, and most likely defeat him when serious, when it comes to serious Juubito and serious Madara, its like a 60-40 chance for both.