Whitebeard's Quakes have smashed through solid rock and shattered steel. If Whitebeard launches one at Hashirama, Hashirama wouldn't be able to counter because all he would see is the air crack, and he'd have no idea what that meant, and while he's trying to figure that out, an invisible attack that he can't sense would slam into his head. This attack, which is capable of shattering steel and smashing solid stone, would be devastating to the human head. Simply falling down too hard can cause fatal brain damage, what do you think an attack like WB's Quakes would do? And Hashirama doesn't walk around with his healing always activated. Unless he activates it right away, which he probably won't, WB can potentially one-shot him. He has to activate the jutsu to auto-heal himself, and that won't happen if he's brain dead.
Now, let's say that Hashi does activate it right away. Then, it would turn into a battle of who is exhausted first. Now, WB was hailed as the strongest man in OP, and people weaker than him were strong enough to fight for multiple days straight, prime WB can fight for at least 10 days straight, as Akainu and Aokiji, who are weaker than him, lasted 10 days straight. Hashirama, on the other hand, lasted one day against Madara. As we saw during the end of their fight, Hashirama was exhausted and had several wounds, meaning his healing has a limit that's less than one day. WB, who can fight for ten days, gets past this.
WB has endurance that can be considered greater than Hashirama's due to the fact that it's all natural, while Hashirama requires a technique. Old Whitebeard took hundreds of bullets, dozens of sword wounds and many cannon ball wounds, got lava punched into his body and half of his head erased before he died. And that's not even his best. There's nothing Hashirama can do to actually put him down. If Hashirama tries to go Sage Mode, WB would take advantage of the brief moment that Hashi has to stay still, slamming him with Quakes. Assuming Hashi's healing is activated, it would still do damage, shattering bones and rupturing organs, most likely delivering injuries that would have killed Hashi if not for healing. While Hashi is recovering and unable to move due to his bones being broken(but healing), WB can keep slamming Quakes on him, turning him into mush buried under rock. Even if Hashi can recover from that, which I doubt he can, WB would have won really cuz he incapacitated Hashirama for a while and can just leave at this point.
If Hashirama manages to use his Bhudda, WB can fight that too. OP has numerous giants that rival the size of the Bhudda, and we saw WB take one down like he was stepping on grapes. That Bhudda can be leveled by a monster Quake to its base, causing it to collapse on itself. The hands try to smash WB, WB puts up a continuous stream of Quakes and Vibrations around himself that cause the hands to be smashed once they reach close proximity to him, not that it would get to the point that Hashirama would be able to use the Bhudda.
Is that good enough for you?
