They're all special shinobi/kages
-First of all minato, flying thunder god, shadowclones, without kurama and amazing s/t jutsu's and summonings he is quiet on par with tobirama.
-third raikage, hell stab, lightning armor and also one of the fastest. Don't underestimate him because he's said to be on bijuu level and his chakra to, fought for days against 10k shinobi army.
-muu/second tschuchikage, chakra transfer, ability to fly and his kekkai tota the particle style. He is stronger as onoki or grandpa tschuchikage. Possible he was also to master of earth style and has some strange abilities besides that.
-second mizukage, don't know much about him but his summoning clam is pretty amazing and he has hydrification technique. I think he's on par with mu
-Last but not least the fourth kazekage, the strongest kazekage of all.
His sand release was special because of the magnet kekkai genkai i believe.
I think hashirama would lose it if the kages would work well together.
More or less they all have there abilities to be kind of unvulnerable. Minato s/t jutsu, 3rd raikage his speed combined with lightning armor, muu his flying technique and strange clone tech, second muzikage his clam technique and fourth kazekage his awesome sand defence on higher level as gaara's ultimate Defence.
On the other hand hashirama's world wide famous wood release, everybody is well known with his abilities so it's not worth to explain.
But 5 amazing and special kages is kind of to much for hashirama, but he would be beaten with extreme high diff
.
