Think back to when Naruto went 8 Tails against Pain, after being buried beneath the Chibaku Tensei. He literally breathed a stream of Fire. In addition to that, think about the Fake Fox Cannon's that he fires earlier on in that fight. They can't be seen as anything but Fire Release, since no Yin/ Yang chakra infusion was performed. The spheres look like compressed Fireball Jutsu.
That was anime, that doesn't happen in the manga, the animators added in that entire fight scene + the fire.
There is literally an orgy of evidence that Kurama's main Element is Fire. Naruto vs Orochimaru, when Orochimaru uses Striking Shadow Snake, the summoned Snake burns up and to escape the imminent immolation Orochimaru performs his Oral Rebirth technique to escape the intense heat that was burning his to ash. The evidence is there, Kurama has an affinity to Fire.
Kurama's V2 chakra cloak causes damage & decomposition, again I think you're referring to the anime. [
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Note the "sfx: decomposition" instead of a "thrashing, fwoom sfx" that ama causes when burning. [
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And in Naruto Storm 3, Fuu can perform various techniques that incorporate her wings and the golden dust it emits. While it isn't confirmed canon, it left the opponent poisoned. That was an example of the Glittery Dust, but it's main focus was to distract, not damage.
Oh I see, well that would be a useful technique to have.
Steam is only usable under steam Armor.
I think Naruto will just get 5-Tails' brute force.
He might of used it when he Blitzed and punched Madara's Truth Rod.
Although Naruto could Mix Fire and Water to create a Steam Ninjutsu.
It's unknown whether steam is just restricted to the armor. SM already gives him a strength boost though.
I doubt he can combine elements on his own, he might be able to use two bijuu powers simultaneously & they might be able to combine their powers but it's unclear.