Itachi definitely wins.
-Jiraiya is never reaching SM when Itachi has the ability to use his Crow clones to prevent him from summoning Ma and Pa for a minute or two. Thus his relevance is massively reduced. He can try to grab it with his hair but it will just disperse into its constituent crows and cast a genjutsu onto him. Jiraiya is weak to genjutsu per his own words, nor can he detect when he is under genjutsu due to a lack of capability to sense chakra flow. Sure, he can summon Toads, but any of them are easily put under Itachi's control and begin attacking the Sannin. Katsuyu ain't doing shit to Bunta, if anything Bunta ends up tying with Katsuyu AND Aoda, since Oro no longer has Manda.
-Summons are sealed via Totsuka stab, and yes, that applies to Katsuyu too who can't split once Totsuka has pierced here, unless someone can prove otherwise. Aoda either loses to Bunta in a long fight, or Itachi seals it and then fights off the Sanin with Bunta and his own capabilities.
-Orochimaru shits his pants when confronting Itachi's genjutsu. He's been caught before, he gets caught again, but make it Tsukiyomi this time.
-Tsunade isn't a great factor here either, she has no way of removing Amateratsu nor does she have a way of preventing it from happening. Or, she just gets genjutsu>Totsuka stabbed.
Inb4 he can't use Susano, Clones, Genjutsu, Amateratsu and Tsukiyomi in a single fight, when he's done much more against Sasuke.
