I thought I'd go back through the manga and create a list of the different moves Naruto has used in his old Kyuubi forms. Some of these we may never see again, but just as the chakra arms have returned so might any of these. And just as the chakra arms have multiplied, any of these might mutate into new and more awesome variants.
Perhaps the most likely to return is the Chakra Roar, seen in both KN0 and
KN3 versions, but any of the following might also appear:
Defensive SphereRanged ShoveGrappling ClawShockwave SwingUnderground SurpriseSplitting ArmsBurning TouchUpper Body BunshinKyuubi PoisonNote that I haven't included the things he's duplicated in RM, like pulling Sasuke towards him for an attack. That's basically the same as pulling Zetsus into a Rasengan. I also haven't included the two Bijuu Bombs, since we know they're returning in the yet-to-be-completed Bijuu Rasengan.
Obviously some of these are more significant than others, and some are more likely to be seen again than others, but I thought it would be good to put them all together in the same thread.
On a side note, since as we know the ordinary Rasengan doesn't work properly in RM, I have a theory that explains how Naruto is suddenly able to form them. Basically, I think what he's actually doing is manipulating the shape of his chakra shroud in the same way that he creates arms. Since a Rasengan is pure Spatial Recomposition, Naruto is able to duplicate it by changing the shape of his shroud. It's not quite the same process but it has the same effect, and it explains why these Rasengans are
the same colour as his shroud and give off the same "flame wisp" effect.Interestingly, by looking back I was able to see that this isn't anything new. In fact Naruto first did this back in Part One, with his original Kyuubi shroud. It looks different, but then the old Kyuubi Mode looks nothing like RM. You can see how he turns the Kyuubi chakra into what I'm now dubbing the original
Shroud Rasengan.