here is proof that tails matter. look at the power difference between the ten tails, and the to remaining bijuu.....the power per tail, goes up exponentially. So in terms of raw power, kurama is the strongest. But as naruto has shown, through spirit and never giving up, you can beat someone who is stronger, so kurama in terms of power, is > all other bijuu, but in terms of strength the bijuu are equal.
Btw shukaku, was never full power vs naruto, and was getting stronger by the moment...naruto only barely was able to stop him, by wakeing up gaara. If he had more time, he wouldve been much to much for naruto, and gamabunta to handle.
