This is only an assumption, but Enton can make Mokuton useless.

[Tyrance sasuke]

Ok, I have proof that Mokuton can burn with regular Katon. Please tell me which proof do you have that Hashirama's Mokuton is fireproof or at least tanked a Katon technique without burning.

Madara's fire katons when they fought in valley of end? He told hashi was stronger than him which means fire is useless against his mokuton, since all his arsenal is wood element.

 

[MightGai]

Madara's fire katons when they fought in valley of end? He told hashi was stronger than him which means fire is useless against his mokuton, since all his arsenal is wood element.

That's not proof. Being stronger than someone else means a lot of things. For example Madara being stronger than Tobirama doesn't mean his Katon is more powerful than Tobirama's Suiton (in any case it would be the other way arround). A being stronger than B doesn't mean A surpases B in every category.

 

[Tyrance sasuke]

That's not proof. Being stronger than someone else means a lot of things. For example Madara being stronger than Tobirama doesn't mean his Katon is more powerful than Tobirama's Suiton (in any case it would be the other way arround). A being stronger than B doesn't mean A surpases B in every category.

We saw how big and intense his katons were in war arc. Had his wood not been resistant, it wouldve been swallowed up whole like all the water jutsu evaporized, even those of mei terumi.

 

[MightGai]

We saw how big and intense his katons were in war arc. Had his wood not been resistant, it wouldve been swallowed up whole like all the water jutsu evaporized, even those of mei terumi.

Did we even see the full fight between Hashirama and Madara to even say that? Also, those big and intense Katons were stopped twice, by some random shinobis and Mei.

Again, I can show you how Mokuton was burned by Katon, but you cannot show me otherwise, and at best you're guessing what happened in a fight we didn't see.