We have no idea how the fight between them went down. You can't use an off-screen fight to show what technique was useless when we didn't even see what techniques were used at all. The only places we actually saw Shisui lose his eye was in the filler and Revolution but both of those are non-canon and involved trickery + multiple people to support Danzo.
Fair point. But if that's the case, you really have nothing to go off of in regards to his body flicker and exactly how fast it was or to what extent it was superior to others. For all we know, it could just barely be better than others' to make him notable or perhaps it was merely is application of the technique.
When did it say it had a cooldown so long? And no, Ao was able to sense it precisely because he wasn't the one being controled. And it wasn't because Ao's words that Mifune got out but because Danzo released the technique. (He was already busted so there was no point in keeping him under control.) Hell, Mifune didn't even realise it after being released and asked Danzo if it was really the case, which Danzo non-challantly confirmed. The victim themselves cannot do anything once they get struck by it precisely because it takes control of their mind (unlike a standard genjutsu which simply manipulates one's senses).
Itachi did when he killed the crow with Shisui's eye in it.
With KA, from what I know of it, it controls one's mind, not their senses like w/ normal genjutsu. So even if Shisui does control Hiashi and makes him want to give up or kill himself or s/m like that, his Byakugan, since his senses would remain unaffected, would still be able to see Shisui's chakra in his body and see his eye's activities activating (just as Neji saw Kidomaru's CM activities activating) and he would know he's in a genjutsu and break out of it. Unless I'm missing something
I don't deny Shisui can pull of a win with KA, but I don't think it's a garuntee it can work.
"Only" as if that's something bad? Anyway, given how you said that he has no feats on what are you basing these are the only things he has? Again, you're just throwing baseless assertions.
He has Sharingan and we saw him using Fireball when Sasuke was a kid.
This is just plain stupid. If you're already going to assume that his attacks would connect then why even bother debating anything? I could just assume before hand that Sakura's kunai will somehow find its way to Itachi's head and gg, Sakura beats Itachi.
Except Itachi has superior feats to Sakura. Just as Hiashi does to Fugaku.
Again, you have nothing to base that on as we never saw him in action and even Hiashi himself has only been shown doing something in a couple of panels as he too is a minor side-character just like the rest. Even if it were granted that Hiashi could beat Fugaku, it still doesn't follow that Fugaku (let alone the three Uchiha we're discussing) are fodder as you'd have us believe
I don't think I called them fodder, and if I did, I meant they would lose to Hiashi, not that they are weak lol