Each genjutsu have specific requires to break it. For IT you need the rinnegan and 9 bijuu chakra to do it, not only the rinnegan because Sasuke wouldn't need Naruto to do it if that was the case. Same thing goes with the strongest genjutsu KA, its counter is no counter and that's something you need to come to. The best thing to do is prevent getting caught in it, just like how Sasuke used his Susanoo to block IT's light. So for Sasuke to not get caught in KA means he needs to prevent the user from catching him in one, and the only way for Rinnegan Sasuke to do that is identify the KA users chakra like Ao did.