Why don't they just use their bugs to try and suck some of the Juubi's chakra? With all the commossion, im sure it can be done. Obito and Madara would probably think it's just any old bug. Sasuke wasn't able to tell when Shino planted a bug on him. The only problem I see with this is the amount of chakra the Juubi has. As stated by the manga, the Juubi's chakra pool is immeasurable but the bugs don't have to take it all since they probably can't. They only have to take enough for a Naruto and B one shot take down. The only other problem they might have is planting a female bug.