That was Naruto's last movie... I'm pretty sure he did or it isn't canon anymore. Idk ask Naruto and ask him why he didn't use it in his last movie :/
Confirmed from facts, nah, from guessing yes.
Exactly. It was Naruto's last movie.
Naruto gained full kurama, and they displayed the feats of what Naruto could do without fully using RSM. You actually think Kishimoto/SP made a movie to nerf Naruto, are you thick? Secondly, show me a scan where it shows Naruto/Sasuke losing their power-ups, oh wait you can't.
Well how come Naruto didn't use his full power when the world was in endangered and to save Hinata? Kumogakure had a cannon to destroy the Moon, and Hinata was in a bird cage. Naruto was fighting Toneri equally in KCM, why would he need to move up another stage? For that fodder? Please.
If you actually believe Naruto lost RSM it's for two reasons:
I. Your a Sasuke fan who hates Naruto.
II. You believe the movie is a legit representation of the manga, when it wasn't even that serious (I saw the movie) --Kishimoto stated it takes place between 699 - 700. Yes, but only to fix his retcon love he never wanted to develop.
Well let me ask you something, IceSlayer. Does Sasuke have Perfect Susano'o? How do you know? He didn't use in the movie? Oh so he only had 35 seconds? The world was in danger Lol. Oh that's right, he solo'd it with a chidori because Sasuke knew that's all he needed to do. Right?
Oh, that's right. Naruto beat Toneri with a full Kurama KCM ... because that's all that was needed.