Board Thread:Theories and Speculation/@comment-27260817-20160131185914/@comment-5936871-20160131215243

Naruto didn't even have the capacity to use any of the other tailed beast's chakra until after he met Hagoromo, and them being controlled by Obito only affects the way they fight. It didn't affect their power, Kurama also only used a casual tailed beast ball to match their combined one with the intent of directing it into the sky to avoid hurting them. If he wanted too, he could have created a much larger and more powerful many times bigger than himself to wipe out the other beasts(as he has done before). Kurama is simply the most powerful of them all, by a ridiculously tremendously amount when half of his power is greater than five of the others combined power. Just look at his ability section on his page, it'll tell you he's the strongest and it cites the chapters.