Pein was talking from within the genjutsu but his body couldn't move an inch so that's not the same case. Frog genjutsu paralyzes the mind and body
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. Same should be for Sasuke and Itachi being in a sound genjutsu that paralyze them since genjutsu affects the brain and their eyes are useless against something that effects their ears so it is a plot hole.
You would be right if you were talking about visual genjutsus, Sharingan is useless against something that affects their ears. Sharingan is totally useless against genjutsu that affects any senses besides sight. The sound genjutsu Kabuto used paralyzes the body, case close but plot hole went around that. Not only did Tayuya's genjutsu completely paralyzed her opponents, Kabuto increased it's power further with his SM. Why couldn't Shikamaru who broke out of Kabuto's genjutsu not bite his lip like Kurenai? He had to break his finger via shadow possession. Sasuke and Itachi using genjutsu isn't that issue, the fact that they can turn their heads and completely go against what the jutsu is made for even thought it's boosted via SM is what makes it plot hole.
Only the 3 Peins that fought Jiraiya were caught in the Genjutsu, the others were getting out of that room and travelling to where Jiraiya was. Jiraiya told Pein his nerve and mind were paralyzed so they couldn't move their body an inch
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The Sasuke and Itachi thing was plot and I mentioned it before but fanboys argued it with no facts at all. First, The Sharingan is useless against genjutsus that affects any other senses besides sight. Tayuya's genjutsu paralyzes people, Shikamaru who escaped Kabuto's genjutsu in the chunin exams couldn't move an inch and had to cause himself pain by using his shadow to break his finger. He couldn't even bite his lip like Kurenai nor could he talk out loud. Not only that but Kabuto increase the Genjutsu power with his SM. It's completely plot.
Same for Izanami and Izanagi. Obito stated you need both Senju and Uchiha DNA yet Itachi tells us many Uchihas would abuse Izanagi so Izanami was created as it's pair. Where did these Uchihas get Senju DNA which was said to be hard to infuse, hence Orochimaru's experiments. Oro was using Hashirama's DNA in his experiments but it's only Hashirama's DNA that they all talk about infusing into them. Itachi doesn't has Senju DNA and if Izanami is a pair to the Izanagi then how was it made to be called izanami's pair or even be at the level of Izanagi? Lots of plot holes until Kishi better explains