Sasuke wins against the sannin,,
-tsunades byakugou is countered through AMA,, as the attack will constantly burn her thus rendering her healing useless,, and making her run out of it,, she also cant attack sasuke with her punches, as sasuke can coat his susanoo in enton,,which backfires it jus like it didd against Ay
-Regardless of jIraiya starting in SM,, its still not perfect as sasuke can flood the battlefield with enton,, and fire enton magatamas and susanoo arrows right on him,,, the summons are sitting ducks against amaterasu and are simply getting burnt,, Orochimarus snake based attacks are alrady known to sasuke and he would beat orochimaru in a similar way like he did in canon
-All the sannin also lack a powerful enough method to penetrate sasukes susanoo,, as V4 or above iis simply too much and also has large AOE attacks that sannin wont effectively evade,, thus giving sasuke the win,,,
Scenario 2 goes to sannin and tobirama,,
mainly due to the fact that tobirama can assist them with FTG, and help them evade everything sasuke throws at them