Danzo, Hanzo, Nidaime Mizukage, 3rd Raikage, gaytachi, and Hiruzen are the only ones i can agree with.
Whose the 5th person?
Anyway all the people i named have significant ways of killing Hashirama
I will only name some reasons for a few of them
Deidara can fly and evade his strongest of techs, while dropping bombs that can blow up large amounts of areas
Hashirama has no ultimate defense nor speed or flying to evade these bombs
Such as C3 and C4
C2 can be a problem as well
He wouldnt even see C4 comming
Nagato CT, Preta path may not work idk for this type of ninjutsu such as wood release
But still he has Human path along with the others
Shinra tensei would obliterate his wood
He can also levitate himself out of the trees range
Gaara
A person who can make just as much sand as Hashirama can make wood
Sand being more flexible already gives Gaara an advantage
Add in that he can fly as well
And can transform the san to fit the occasion
Ex: if Hashirama uses flowering world tree
Gaara can make an umbrella made of sand or wrap himself in a ball
In which Hashirama has no way of getting through
Or he can simply fly to avoid it
Gaara can also easily use the sand underground to sink Hashirama.
Attacking while defending is something i cant see Hashirama beating.
Idk why you said 2nd Mizukage and not some of the other people, cause he has less chances of winning then some of the other people i named (fanboy)
Like Muu or Oonoki
Dust release can destroy Hashiramas biggest tree as seen in the manga and even perfect susanoo clones whom are just as big
