Amaterasu, Genjutsu, Tsukuyomi or Totsuka.
Take your pick.
lol body shedding says hello to amatratsu
totsaka has no speed feats it only sealed somethign the size of a bijuu and a crippled mind controlled nagato
we seen normal genjutsu that itachi did on him does not solo orochimaru prob because he is ranked so high in genjutsu.... look up his stats
tsyukiomi yes this would be downfall for orochimaru i think
but itachi beats oro (meaning the feats we have seen we do not know what else orochimaru has up his sleeve) no less then high diff the first time we seen them fight it wasnt even a fight orochimaru simply wanted itachi body he didnt even put up fight all he did was resisted a genjutsu ppl act as if orochimaru actually got defeated. second time was oro fault for talking to much and not paying attention to itachi and getting sealed. btw itachi knew he couldnt beat orochimaru hydra form so he had no other choice but to seal it
curious does genjutsu work on a zetsu body i was under the impression they dont have a brain or blood? (like they dont need to eat or poop or drink water etc all which helps brain function and get stronger) if this is case i change my vote to orochimaru taking itachi high diff as all his best moves bar tsyukiomi can easily be countered by what orochimaru has shown and with his mayflay tech (even without it he could still merge in ground before) can easily go under the susanno and kansanji his heart..