!st path Animal path
Hashirama has fought several tailed beasts and with mokuton can restrict movement of them. I know that mokuton has the ability to drain chakra from stuff but he wouldnt have to do so for non-tailed animals since summons are considerably weaker.
2nd path Asura path
Hashirama can regenerate himself better than tsunade who can heal herself extremely fast and most of these robotic abilities are blasting things or extra arms. Hashirama can grow mokuton from his own body and escape grabs or block any of these attacks and if he is hit he can heal himself and counter.
3rd path Petra path
So I have looked it over and i believe that mokuton can be absorbed with petra path. But petra path is not always active and by that i mean it isn't automatic but my counter to this is that Hashirama used a lot of weapons to fight and with mokuton+weapons he can hit nagato pretty easily.
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Now dont flame i know this is 100% non cannon but this is what he can do and the picture of him with the weapons around him proves that he used weapons well enough to use them in a real battle.
4th path of pain Human path
As we saw in the battle against Naruto bee vs. Nagato human path is not automatic. If hashirama gets caught in this he can push himself away or attack Nagato with weapons or weapon summons. But for this i dont believe Hashirama will get close enough to let Nagato use this technique on him.
5th path Naraka path
Only relevent when the human path is used.
6th path Deva path
so Hashirama can counter this in many ways for starters his push and pull abilities can be stopped by using mokuton to hold himself down or he can attack and counter Nagato while being pulled. As for shinra tensai Nagato has a five second interval and can be attacked easily from the ground by Hashirama so it would be easy to get him that way. As for a shinra tensai on the scale of the one that destroyed kanoha, Hashirama can use mokuton to defend himself and cushion the blow and heal right afterwards and Nagato's deva ability would be down for a while which gives Hashirama a big upper hand.
Chibaku tensai can be countered by mokuton through the use of growing trees! since chibaku tensai does not immidiatly pull you up there it can be beat before you leave the ground! as soon as some trees are up there Hashirama can grow the trees through the rock to the core and destroy it from there.
Gedo Mazo is countered by using mokuton to drain its chakra
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Now where it gets fun is Hashirama and his Mokuton his ability to chnge the battlefield create poison flowers that can knock unconciouss kage level ninja
use bringer of darkness which will stop him from seeing chakra.
and i would like another post to see where in the manga it says he can see chakra because it could have helped him here
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here (read chapter and one after it)
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and here
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But this is my reasoning as to why Hashirama beats Nagato