Itachi vs Deidara

he only train it to counter normal genjutsu rite??tsukuyomi will still work rite??cuz tsukuyomi is not like other genjutsu..

even dow he trained he will still lose

Think about it, yes sasuke beat deidara, sasuke beat itachi, but sasuke only beat deidara in the end because of his lightening based attacks, which I dont believe Itachi has. Therefore c4 would effect him which alone is a hard thing to avoid, on top of that the c2 dragon/ landmine plan would work on itachi because once again he has no lightening attacks. And finally genjutsu cant work on him, maybe itachi MS can but we cant really assume it does. So id have to go for Deidara on this one he has defence against itachi's genjutsu, and in the end yea he isnt the best at taijutsu but he is good at avoiding things, with the fact e can fly and that he avoided gai, rock lee, and neji with no arms.

It's a toss up to me. Itachi still had unknow techs that Sasuke didn't have, he just doesn't have the elemental advantage like Sasuke had in his fight with Deidara.

Itachi also has the perfect defense Susanoo Deidara loses Itachi flawless victory

Deidara is good as dead...Itachi is too powerful for him.

well after thinking about it Deidara is a very deadly character. if he can avoid Itachi's initial g=enjutsu attacks he might be able to win.

Deidara has trained to counter the sharingan, but can he counter the mangekyo sharingan? He has knowledge on it but does he know how it works and such? Doubt he will has anything on Sasunoo.