Itachi and sasuke can win this
lets bear in mind that sasuke is more powerful now than he was when he fought the kages. also he hasnt just finished defeating danzo so he's super energetic.....
A- his fighting style is close range based and itachi,being so skillful, can put him in a genjutsu before he can actually attack.
Tsunade- she's still alive now cuz of her ability to heal, but shes not that fast. with sasukes sword moves and raiton, he can use the jutsu he used to cut Diedaras birds wing to cut her head off while shes charging
Mei- suiton loses to raiton(sasuke) 4 out of 5
Gaara- sasuke could just use amaterasu on the sand when its protecting gaara from itachis move to create an oven and when she lets her guard down itachi can finish him off
Onoki- he would be their greatest challenge but they would be able to pull it off, seeing how sasuke got rid of the zetsus without even moving
Lets also bear in mind the move the brothers did when fighting with kabuto(also the giant pig) with their susanos
Bottomline: the brothers might be able to win. but am not saying the kages are completely out
I'm glad you chose to provide a reason for each claim. Let me see if i can't disprove you!
A- True, he is a close ranged fighter -From what we saw in Sasuke's fight. Whose to say he hasn't got something more up his sleeve. True he's impulsive and hot headed but so's Naruto. And compared to Itachi A's chakra reserves are much more.
Tsunade - You say her healing is not fast? Thanks to her new technique Byakugou she got a Huge sword shoved through her and managed to heal instantly, I'd say she's insanely fast with healing. Also she managed to break through Madara's susanoo and let's face it, Madara's much stronger than sasuke.
Mei: True Suiton looses to Raiton. But excuse me? Mei does not use suiton at all. She mainly uses her two kekke genkai. The lava release which could burn sasuke out in an instant and if he defends with susanoo she has already shown her ability to corrode it with her boil release.
Gaara- I have no idea what you just said for Gaara. Where does a she or an oven come into this? Gaara can protect himself against amaterasu and tsukuyomi with his sand. Susanoo may be a problem for him . But now he's got the gold dust as well.
Onoki - I don't see how zetsu can compare with Onoki. True Sasuke did get rid of them before moving but they weren't floating. Onoki can move away from sasuke's range by flying and can still attack from any point he wishes. And since he's Tsuchikage I'd say he has some nifty earth-release moves too.
Well that's my counter attack on your logic. A few more things. Itachi's stamina is low. Apart from that he always tries to protect Sasuke who is brash and overconfident in battle. This could lead to itachi injuring himself and sasuke getting himself killed. Sasuke also overuses his technique to the point of death. Feel free to rebuke me but with proper reasoning please.