The transformation was separate because they lived separate the ninetails finally gave up complete control to Naruto the ninetails stated he would rather be controlled by Naruto then controlled by Madera he respects Naruto as a warrior now so they fight side by side Naruto called Kurama his comrade from the leaf and Kurama is finally down for the cause. At this point Naruto can't be defeated Sasuke doesnt have a snowballs chance in hell in defeating Naruto now for sure if you dought me realize he's about to destroy five tailed beast and that masked nutbag who ever he is I'm thinking it's Madera's brother when he whoops all of them what's a little Uchiha in comparison.
well not to sound like a "fanboy" but sasuke is a really hard snobi to beat.
1.He has kumi(just as fast if not faster then the KM).
2.He has ameratsu which is a one hit ok if naruto is touched.
3. He has the ameratsu arow(which is almost as fast as kumi and has longer distance)
4. a EMS sunnosso is no push-over
5. He was shown to be able to disperce kurama's chakara
6. His regular sharingun can control even the toughest summons. Madara was shown to be able to control the fox even sealed within a host. (plausable now that sasuke can do the same with ems)
Yes naruto is BA but don't forget that sasuke has traditionally been ahead of naruto in almost every catagory.