If kisame was to counter and break itachi's countless genjutsu then i agree it would be an interesting fight, since it would most likely take place in a place with water going by kisame's fighting style.
We do know that itachi being a suiton user but also a sharingan user should counter any suiton kisame uses. Katon isnt effective here, but amaterasu is no ordinary katon jutsu. Not even water can extinguish it. Note that kisame isnt fast enough with a speed rating of 4/5.
If he cannot evade A's lariat, he isnt evading amaterasu. Look at it this way. Kisame can evade amaterasu if he swims, but there is one problem. He doesnt have the speed or reaction feat to evade such an attack. As for tsukuyomi, it might be short range, but itachi was able to burst into crows and with great speed came close to sasuke and activated tsukuyomi.