Shisui has no canon, on panel, feats so it can't be determined.
Yes he has. 300-400 feet 3 tomes genjutsu on multiple people at the same time(still very powerful). Im sure even ms itachi can not do that
To me he sure looked like a superior of the two. His Shunshin was as said by his hype was awesome. Also his genjustsus were out of this world, even Itachi who's known as a great genjutsu user can't match it. Ao fled the battlefield when he saw it was Shisui!!
Itachi also said that Shisui was the main force from the Uchiha side, with him gone the Coup didn't seem like happening.
So was Shisui better than Itachi?
I think MS Itachi is better but not by much.
While they were alive Shisui was better.
biggest dumbass on narutobase, Danzo beat shisui with one hand and took him 3 seconds. So I guess shisui is almost as strong as nagato/obito/kabuto ect
Well, Itachi was 12 at the time and Shisui was anywhere from 18-24. He probably had more experience. But that's all.
Itachi is pretty proficient at body flicker and was fast even at the age of 12. Itachi was praised as a prodigy, whereas Shisui was not. Also this is filler and the part of Ao contradicts canon, because in the manga Ao stated that he actually fought against Shisui in a 1v1 fight and saw his MS. Itachi was also Shisui's best friend and it is quite evident that they trained together, so Itachi probably mastered his moves and improved upon them later on. Itachi also has much better genjutsu feats than Shisui and is the only Uchiha we've seen to cast non-ocular genjutsu. Itachi also awakened all 3 techs of MS, whereas Shisui like Obito, only awakened one OP tech. Even then, Shisui's KA is not very suitable for battle considering he can only use it once every ten years.
Also, looking at the way they acted, even then Itachi seemed to be the better ninja. Itachi always had his guard up, even then. Shisui 100% let down his guard when he caught Danzo in that 3-tomoe genjutsu and even took the time to tell him when he would get out of it (which was pointless, because Danzo would know when he was free lol) instead of being smart and just ditching while he could. That resulted in him getting neg-diffed by Danzo with just one arm.
Itachi never stated that Shisui was the main force of the Uchiha in the filler. He stated that he was ONE of them and Hiruzen agreed that due to that the coup would surely fail. Itachi was the other. U_U
So, no. Even back then Itachi was better than Shisui.
You call him dumbass yet you're using anime filler as a reference.
Sushi hype is mainly from his teloport jutsu. He never spam ka unlike obito. Of course he let his guard down against danzo because he thought he gg danzo. Sasuke got caught off guard too. Like you said they trained together, so its even more unreasonable to say sushi strong only due to op ms. Itachi looked up to sushi in every way. Itachi is equal to sushi the most. Genjutsu wise, sushi is better(not talking about ka)
He couldn't spam KA, he could only use it once every ten years.
He looked up to Shisui for his beliefs, not power.
Equal? Maybe when Itachi was a young child, but around the point that Shisui died, no. Nor afterwards.
Genjutsu wise, Shisui isn't close to Itachi considering that Itachi can do everything he can do except better, minus KA (which doesn't help much considering it's not good for combat an a one-in-a-decade oneshot). Tsukiyomi is actually better because it can be used multiple times and doesn't have a cool down.
KA this and KA that. Danzo got passed it and ripped the man eye out in 5 seconds flat.
When Shisui defeats Itachi, then I will believe that he is better but for now. Itachi > Shisui.