Itachi decides to just out and out slaughter the Akatsuki when Tobi and Pain are away. The fight takes place in Fake Karakura Town. There will be two rounds.
Round 1: Itachi fights them one on one with no rest in between. This is the order.
Hidan
Zetsu
Konan
Kakuzu
Deidara
Sasori
Kisame
Round 2: All of the above take on Itachi at once.
Itachi starts both rounds healthy and PIS/CIS is off for all competitors.
Itachi's already one-paneled Deidara with a casual genjutsu. Other ones won't fare much better either other than Sasori who is pretty much immune to genjutsu.
Itachi's not having trouble with any of these guys solo. Even as a team, they really can't do anything once Susano'o is up.
Kakuzu is a bit tougher, but a well-placed Amaterasu should finish it, which is a problem. Itachi lacks stamina, so using his big techs are going to be draining.
Itachi has shown he can easily defeat Deidara.
Sasori will be much tougher, he can tell Itachi's best Genjutsu to eat shit, and he has enough methods to misdirect attacks and dodge them that Amaterasu is unlikely to land a solid hit, though any puppet that takes that blow is toast. Which means Itachi will have to use Susano'o, which indeed would put down Sasori.
Last and most challenging is of course Kisame. It is here that I think Itachi probably falls. Already having used Susano'o on Sasori, Itachi's chakra is going to be less than half full, maybe dangerously low. Which is very bad when fighting someone who has "drains chakra" in his powerset, and who can outmaneuver him using his impressive battlefield control abilities (Moving testicle of the leviathan), and it must be said that Kisame starts with considerably more chakra at base than Itachi does healthy, his chakra being explicitly comparable to a Biju. Fighting all of them at once? Itachi has no real chance.
One on one, Itachi would handle any of these guys, sure, but see, while being a more powerful combatant than any of them, and being generally impressive in almost all ways, Itachi actually has relatively low chakra for an S rank ninja. He simply doesn't have the stamina to take them all on in a row no rest, or take them on all at once.
Keep in mind Deidara explicitly trained his left eye to see through genjutsu. The one Sasuke used on him during the fight was apparently the same one and Deidara had no problem seeing through it.
I'd think Konan'd need an amaterasu too. She can use paper and clones to avoid eye contact, and most of his normal jutsu aren't going to do much to her paper body (she was able to stop Jiraiya's fire jutsu, so Itachi's fireball isn't going to be much different).
Konan was at that point out of chakra to the point of being unable to use her paper form (which she's normally in constantly and is a major facet of her defense), let alone clones and such, and Obito had used up an eye in Izanagi so he was uninjured and healthy.
Normally try and grab Konan and you'll be cut by paper or have tags blow you up. That's what happened to Obito the first time after all.
Itachi would beat up non-Jinchuriki Obito casually. Dude lost to Kakashi, someone who Itachi toyed with on two different occasions. Obito can't even use Amaterasu, Susano'o, or Tsukuyomi either since he needs Mangekyou Sharingan in both eyes.
Konan lost to Obito with a ton of prep and even knew his technique's weakness. She wouldn't be a problem at all :/
Kisame, Sasori, and Kakuzu are the only ones who can do anything, really. And that wouldn't be the case once Susano'o is up.
Yea, Kakashi didn't have kamui when he fought Itachi. First time, no kamui. Second time, only slow, inaccurate kamui. Obito? Fast, precise, repeated kamuis.
Ok, I guess that's due to the damage from being from earlier.
Still, he's part Zetsu. He can fight without a *heart*, and she was exhausted and had done way more jutsu.
Itachi wasn't using Mangekyou Sharingan though. That alone more than makes up for Kakashi lack of experience with MS since Itachi's Mangekyou Sharingan >>>> Kakashi's. And Obito at that point had a Rinnegan as well.
Yeah Itachi would loose against Sharingan Obito more often than anything. I mean he does have Izanagi in case Itachi gets a good hit in and I'm not sure genjutsu would do much of anything.
As for this gauntlet, Itachi stops at Sasori. Genjutsu is useless an Amateratsu shots are limited. Then again there is Susanoo but shouldn't he be taxed out by that point?
Oh and does Itachi get Izanami for this gauntlet? Because if he does then he could probably clear.