madara and naruto are a stretch, but at this point he should be able to beat nagato. He's about as strong as naruto was before he gained control of the kyubi. & he fought the kages successfully back when he had ms and he killed one, and took another ones arms, seeing as how he's stronger now, it's not that far fetched to say he could solo them. As far as itachi goes, it's yes and no. No he couldn't have beaten itachi with his sealing sword and mirror shield, but if you took that away from him yes he could have. Itachi fought sasuke to exhaustion, even using his life force as chakra, in order to deplete sasuke's chakra reserve enough for oro to come out so he could seal him. If this wasn't his goal, he could have easily sealed sasuke, but it wasn't, so he had to fight sasuke as if he didn't have the sealing as an option, and sasuke was stronger. He broke out of tsukyomi with a regular sharingan, his fire jutsu proved stronger, he proved that if itachi had to fight him without sealing him, sasuke would win. Also let's not forget that sasuke has done something no one else has done, control amaterasu, and during his fight with the kages he proved to be faster than the raikage with lighting armor v1. The raikages lighting armor v2 would undoubtedly be faster than sasuke at this point, but the raikage is also the 2nd fastest living shinobi in the world right now, which would probably make sasuke the second fastest (without counting 8 gates gai and lee) or at least top 5.
He's strong, for some reason though, people either like to go overboard (he can solo madara) or the won't give him any credit at all.
out of the living (non edo) shinobi, the only people who could possibly beat him, imo, are naruto, 8 gates gai, and possibly tobi.
