I made a thread on this from a while ago with AkatsukiChurch establishing why I think he would win. Separately as a team, I think Sasuke would win, but if you had a hypothetical fusion of the Gokage in one body, that "person" would win. Problem with them as a team against Sasuke is that all but Gaara and Ay have countermeasures for instant Amaterasu snipes. Tsunade and Mei are uncharacteristically slow and Ohnoki is an easy target while floating for someone with a Sharingan. If this was in character, Sasuke would likely lose because he wouldn't have a full mindset to kill right away. But given the stipulations in the OP, Sasuke should not have any problems with this. Tsunade and Mei don't have much to stop getting sniped and burned and they're extremely integral to the Gokage team given Mei's Ninjutsu versatility, her Acid Mist and Tsunade being the only medic on the team. With them gone, Sasuke would do the same to Ohnoki and then the real battle starts. Sasuke can instantly go Susano'o and give him access to Susano'o Arrows that Ohnoki has no canonical feat that he can react to something that needed Kamui to warp away, and then Gaara and Ay have no conceivable way of getting through Sasuke's Susano'o (nor would the sand method work since the sand has to be lightened, but in this case, Sasuke snipes Ohnoki to prevent that from happening). Then it becomes a big old wild hunt. Sasuke repeatedly slams both of them with his Final Susano'o Enton Sword and ends them.