I agree with everything except the first part. Naruto Was only able to use 2 rasen shurikens before SM was gone but don't forget that Naruto had 3 shodow clones gathering natural chakra from him. Shadow clones splits Naruto's chakra among them, if Naruto made 3 clones then he would have 25% of his chakra. This is from way back in the chunin exams when Neji couldn't tell which one was which because they all hd the same amount of chakra also when the 8 tails explained using clones would only make Kurama eat more of his chakra. So each clone also could use 2 rasen shuriken as well mking Naruto's out put in SM 8 rasen shurikens. Plus now that Naruto is friends with Kurama he can fuse with Ma and Pa and use as many rasen shuriken as he wants. Plus there's frog song.