Well I really didn't see Sasuke having any trouble against Naruto prior to that moment... and by that logic Naruto shouldn't get a pass because he's had "borrowed" power his entire life. And they both got their op power ups from my the sage so please just stop it with the bs.
Yes Naruto has had Kurama's power all his life but he doesn't really rely on it, instead Kurama gives it to him in an attempt to weaken the seal, btw Naruto went out to learn Frog Senjutsu. Speaking of Sasuke, without his sharingan he will be a less than average ninja cos Neji and Lee and even Chouji will stomp him. Plus he has borrowed powers as well through Itachi's sharingan too; if not he would have been blind by now, so SHUT IT!
They both have Powers from SO6P, but Sasuke clearly feels the need to surmount more powers to battle Naruto because he clearly feels that he needs more powers to battle a resilient Naruto who he saw kicking Kaguya's ass, so he doesn't want to take any chances of that happening because he powers are not even up to Kaguya's. Meaning that according to the law of transitivity (if A=B and B=C, then A=C); if Naruto can beat Kaguya, the same Kaguya that smacked Sasuke several times, then it implies that Naruto can beat him.
Now Sasuke's battle strategy is no longer based on his ability to uses the resources that he has in a crafty way but it is now based on POWER. Whereas, Naruto is basing his strategy on what he has always used which is his resilience, his ninja way of not giving up, his love and Kurama chakra plus all the powers that he cultivated himself plus a little help from SO6P (btw he should be able to use YANG release very soon I believe). Too much power corrupts clear thinking in battle, we have seen it several times in Naruto manga, and the latest to show this were Obito, Madara and Kaguya.
We know how Naruto manga has always worked; The underdog wins the battles… in this case, Sasuke has given the victory to Naruto by choosing to be the chief dog, and making Naruto an underdog.
TBH, Sasuke has alway required more powers to battle Naruto even in their first first at the valley. Naruto was using one tail kurama chakra cloak and a small rasengan only (even though he had summoning which he used against gaara and multi-shadow clones in one tail cloak mode) but Sasuke was using Curse seal LEVEL 2, Chidori (infact it was a black chidori), fireball jutsus, and finally 3 TOME SHARINGAN.
(NOTE: These are the same battle abilities that he used on OROCHIMARU, DEIDARA, AND ITACHI)
looooool, Sasuke always requires higher power against only Naruto, and the question is why??? It is because he feels Naruto is stronger each time… At the Valley it was because he had seen the power of Naruto's Rasengan and it effect on the water tank compared to his chidori effect; now it is because he has seen the amount of chakra that Naruto wields and control when he was fighting OBITO and KAGUYA
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