Sasuke should win both scenarios.
S1: Juubito's Gudo Dama explosion is the only technique that'll could be an issue, mainly because we don't know how powerful it really is. Obito was able to tank one with another Gudo Dama, while Naruto's Senjutsu Bijuu Dama was cracking the Gudo Dama, so I don't think its as powerful as a Bijuu Dama. It wasn't negated either since they orbs contain Rikudo Senjutsu. Obito was able to use a Gudo Dama shield to block Sasuke's attacks in canon, but he can't manipulate it to that extent in this state, so he can't block Sasuke's attacks here. He can't evade them either. Both Naruto and Sasuke couldn't hit him before,
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, and Sasuke started to be able to see his movements, (So no, no one is getting blitzed, especially since the gaps in Juubito's actions due to his state, and the fact that Sasuke knows what to expect, means he'll enter Susanoo ASAP)
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So Sasuke should take this, if I'm not forgetting about any of Juubito's capabilities.
S2: Same as above basically, but instead of attacking with a Senjutsu V3 Susanoo, he attacks Juubito with a Senjutsu enhanced Perfect Susanoo armored onto Full Kurama. The Bijuu Dama barrage should end Juubito. While the Dama aren't Senjutsu themselves, they can still wreck the Gudo Dama as they can't negate Senjutsu when Obito is like this, and the blades themselves would be Senjutsu as they come from Sasuke's Susanoo, so they should cut him to bits before exploding.
