Alright, here we go
1Tobirama counters Tsukuyomi quite easily, he has plenty of experience fighting the Uchiha so he knows he shouldn't look into their eyes. This does make him susceptible to Amaterasu, but we know he can teleport anything he touches, so basically he could take Amaterasu and teleport it to Itachi, as he did with the Bijuudama. [
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gg
2Now before this even happens, Tobirama makes shadow clones, which he always does. These clones can help him navigate through the battlefield with FTG and can help him disrupt his chakra flow in case he gets caught in genjutsu, yet again since he has experience with fighting the Uchiha, this something he'll very likely do.
He counters Katon with Suiton, not debatable.
3Now, assuming Itachi isn't dead yet, and he uses Susano'o...
Tobirama can use his 3 edo's and shadow clones to surround Itachi, since the Yata mirror isn't 360 degrees, he can't defend himself from all directions. Yet again, Tobirama has experience with fighting Susano'o as we know he participated in fighting Madara, since Danzo almost managed to penetrate Sasuke's Susano'o weak spot, Tobirama can use
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jutsu to tear Itachi's Susano'o apart. We all know how much trouble Sasuke had with sustaining his Susano'o, so for Itachi to perform Complete Susano'o takes quite a toll on his body, especially when attacked.
4While outside of Susano'o, Itachi doesn't have many counters to Suiton, since Katon is out of the question, and Itachi has only shown one Suiton technique so far which required a water source. Suiton's general destructive power will surely pressure Itachi, and use of MS techniques will render him fatigued rather quickly.
I'd say Tobirama takes this mid-high diff...