My argument is: Naruto at the Valley of the End would be Moon level. He clashed with Sasuke, who was out to kill Naruto, after he attained the Rinnegan and had already grown accustomed to his superpower, post-Kaguya fight, and then proceeded to battle him to near-death after they clashed their avatars together; of course, in the latter half of that slugfest, Naruto struck Sasuke in the face and damaged his eye, but he still fought with a, albeit weakened, Rinnegan Sasuke. Even then, his Rinnegan was just damaged—really, it was just his face and not his actual eye—not destroyed, so he would still have some power; as Kurama noted, his Rinnegan had simply weakened. Along with that, Hagoromo previously shared half of his own power with Naruto, which enabled him to use Six Paths Sage Mode.
Although, you could completely destroy this argument by downscaling Rinnegan Sasuke's physicals to below Moon level, which would not work, given the Rinnegan grants the wielder a power boost, and a god-like one at that.
Now, this is where a lot of people get turned off.
Funnily enough, the current scaling itself is kinda circular. Kaguya is superior to Hagoromo, who needed to combine his powers with those of his brother Hamura in order to seal her away. Madara, with one Rinnegan, was stated to have been approaching Hagoromo's power. Hagoromo then shared half of his power with Naruto and half of his power with Sasuke, who then battled with Madara, and then again after he acquired a second Rinnegan. Rather or not Madara reached Hagoromo's level after acquiring the full power of the Rinnegan is up for debate, but that does not matter, because Naruto and Sasuke then go onto battle with Kaguya, and actually held their own against her, Naruto especially, before sealing her away with the power that Hagoromo gave them. What that means is: One Rinnegan Madara (approaching Hagoromo's power) < Dual Rinnegan Madara < Hagoromo < SPSM Naruto and Rinnegan Sasuke (with 50% of Hagoromo's power) ~< Kaguya < SPSM Naruto and Rinnegan Sasuke's combined forces (100% of Hagoromo's power) ~ Hagoromo and Hamura's combined forces. Right?
If Sasuke scales to Six Paths Sage Mode Naruto, how come base Naruto scales to him?
That's a good question. I have no answer. The only solution I have is to ditch their slugfest altogether—just act like it never happened even though it did.
Or we could actually downgrade his physicals, since Nagato wasn't 5-C.
But of course, that's War Arc Naruto.
Adult Naruto scales above base Momoshiki for being able to briefly hold his own against Fused Momoshiki, although he ultimately felt the need to use Six Paths Sage Mode against him. Momoshiki also considered Naruto's chakra ridiculously enormous as he drained him and even gave up half-way through because extracting Naruto's chakra was taking too long. He also briefly boxed with Delta in his base, although Delta was not really trying there, so he would not scale using that.
That's really all I got. I'm groggy.
