Actually "some" of the White zetsus were made from hashiramas Cells, also dont forget Yamato's cells were used to make the Zetsus stronger, Yamato's cells is a weak copy of Hashiramas.I disagree.
That's not possible because all zetsu are people who were once put into IT and Hashirama's cells never made white zetsus,. Black Zetsu simply tricked Madara into thinking that. (It is a retcon)
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As for Black Zetsu giving Hashirama life energy, how? Also, why?
I know you said it was to inspire Madara or whatever but Hashirama said he was soft hearted (probably not power hungry?) until Izuna died but Hashirama already had Mokuton by then.
I'm not saying it's impossible (it is Kishimoto we are talking about here, he makes plot holes all the time) but it probably wasn't him.
As for the Ootsuki's, it's likely but I want to know why him?
As for Why hashirama, because he was Ashuras Reincarnation I would say
Indra and Ashuras descendants have been at war ever since, and it was black zetsu who changed the tablet "that power is the answer" to cause it.
Obviously he wanted them to Seek power, same for Madara, and the best way for that is to have a Rival to compete with, to want to Surpass, Since hashi was already ashuras Reincarnation, he was the most sensible choice