This is what I'm trying to figure out. Sick Itachi can't even hold up susanoo that long and he was getting outclassed by hebi Sasuke most of their fight (even if he was holding back Sasuke was still outperforming him with katon, shurikenjutsu, and broke out of tsukuyomi).
You guys keep saying "Itachi can't hold Susanoo long" as if he needs to hold it long against a Madara who can't do anything to stop it in the first place. :lol If the argument here is "Madara runs around Susanoo until Itachi tires out" then you can stop now. Madara hasn't shown the speed to evade Itachi long enough for him to actually tire the latter out either. With a Shunshin he was able to catch SM Naruto off guard. That's not speed that lets him do what I know you people are thinking he'll be able to do, and that's Shunshin, a burst of speed. Not continuous movement. :lol That's why KCM Naruto gets tagged by people who can't match his Shunshin speed.
Itachi after using Amaterasu multiple times, using Tsukuyomi and having it broken along with other jutsu was still able to hold a level 3 and 4 Susanoo up for around 5-10 minutes. Itachi doesn't need anything above Ribcage to deal with Madara. V2 and up is massive overkill. And Sasuke outperforming a holding back Itachi isn't something worth mentioning here.
Itachi engages Madara and then crushes him low difficulty. No 3-Tomoe user without a special subset of abilities is going to take out any MS user who can use Susanoo and Amaterasu.