I'd have to disagree with Kiba slicing through the rubber god's defense if he didn't control the absolute properties of Rubber:
Here Dodai is shown to manipulate liquefied Rubber - Lava Style of course consist of two elements Fire & Earth, using Fire Dodai heats up the Rubber, and can control it in its liquidized state:
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Then there's the manipulation of Rubber in its solid form as seen here:
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Kiba's technique is a linear, spiraling, piercing technique (it's piercing correct?). The reason why the technique wouldn't pierce through Rubber God's defense is because of this:
Spiraling . Either in liquid, or solid form the spiraling addition needed for Kiba's technique is what gives him the L.
Against the liquefied Rubber Kiba would spin himself into basically what Neji had spun himself into, a sticky situation (no pun intended) this would not only slow his spinning movement down, but as well restrict it - One could even argue that the rubber would negate the initial spiraling motion: Meaning it would shoot him back the way he came in a counter-clockwise momentum.
Against the solidified rubber the spiraling motion would act more as a blunt counter-face, this would replicate exactly what Sandaime Raikage performed on Dodai's rubber ball; sending it flying away, but not breaking it.
He literally had to cut straight forward in a linear motion to sever the solidified rubber in two something Kiba does not possess from my knowledge.
Educate me though fam, I don't know much about the Dog Sage.
He's basically impervious to anything that's Taijutsu.
