@Unbiased King,
Agreed, the 3rd will likely inhale the pollen and suffer those effects, but how would that kill him? A battle is usually decided by the last one breathing; if both still breathe, who wins? I think it's unfair to say that lulling the 3rd to sleep constitutes a win.
One loses the battle if he's not able to fight anymore, the death itself is not the only way to win a fight, taken Tsukuyomi as an example, which let you fall in coma after enduring its effects. Once the third Raikage inhaled the pollen, he's left paralyzed or asleep without being able to move. Hashirama could simply crush him with a single Mokuton technique, if he's lying on the ground without protecting himself.
So how can his strong, incontrollable genes that have the power to reduce technique intervals from 10 years down to a few hours be avantageous against the Raikage? Also, where/when is it stated/shown that Senju cells give a power boost? Or did you mean chakra? In that case, both the Raikage and Hashi have enormous chakra levels, being that the former fought for 3 days straight and died only from exhaustion.
I just wanted to clarify, that Hashirama has a great stamina, too. Everyone's seeking for a part of his power, he created a village, he created a valley in a fight with Madara.
Once again, how is this helpful to Hashi in his battle against the 3rd?
You should remember, that Naruto used his sensory ability, in order to go with the third's moves and push his hell stab into his own chest; the ability to sense the opponents techniques is just another benefit.
Sure it's larger than a biju, but it has been said to be equivalent in power to one (not specfically any beast), so how can the power be scaled? Especially in an argument of A>B, B>C, so therefore A>C. This is not the case in Naruto; the squeeze theorem does not apply.
ABC logic indeed works, as both the Bijus, Raikages and perfect Susanoos concept is based on destructive power, and the perfect Susanoo is by far superior to the other Biju, except of Kurama. Madara most likely referred to a single slash when comparing it with the Biju itself. This Susanoo is not only huger, it doesn't feel pain and can rebuild damaged parts of its body. The Akatsuki pairings have caught most of the Jinchuriki, though latter were pretty much good Jinchurikis, Kakuzu and Hidan even faced the full two tails. Madaras Susanoo however was going to crush the five Kage with a single stroke, it would easily destroy the most Biju. If Hashirama beat such a monstrosity, he will beat a human, too.