Koto is allowed.
R1: Hidan. R2:Mei. R3: Part 1 Hashirama. R4:Anbu MS itachi. R5:Alive Minato R6:Orange mask obito.
With Koto allowed there's no reason why he couldn't beat all of them (assuming these aren't back to back fights). Without it he probably stops at Hashirama since we haven't seen any sealing jutsu from him.
