From experience most of these guys are usually mid-late game champs, if you have trouble playing against most of these champs and feeding them then I will stress very hard on the “pussy” playstyle where you just sit back early and farm up without giving them the chance to jump on you and kill you.
Sadly most of the champs you listed are very powerful in mid which I almost never play, but I do know that all of these guys excel with killing and snowballing a lane when against a squishy opponent. Like Irelia, Yasuo and Akali (akali’s second ult deals more damage the lower the enemy’s hp is, so she is good against squishies because she can burst them down low enough with basic combo to execute with R)
And btw most of the champs you listed are all either assassins or play in an assassin like way. Akali and Zed are made to dash in, burst a key target and dash out before the enemy has time to react. If Akali, Zed and other assassins can’t reliably do their jobs then they are useless to the team, so your job when going against them is to stop them from getting fed and/or scale to the point that they can burst squishies in the mid game.
They can’t really be nerfed a lot because if they get gutted/nerfed far enough then they become useless and basically a troll pick. Understanding balance changes also requires you to understand the concepts and design focuses of certain classes and the champs. Assassins have to be able to burst a squishy target at around 1-2 items (this is around when mid game happens, usually the first turret(s) have fallen and everybody has fully completed at least one item) because mid game is also the time where the juggernauts don’t have their first set of resistance items completed, the supps don’t have enough items to fully counter them, and just overall everybody is weak enough that the Assassins can do their jobs the easiest.
(Btw I don’t play any assassins at all, I just pay attention to design details and I understand concepts a lot)
Diana needs a fuck ton of AP for her to reach her assassin point, so if you can prevent her from snowballing during the early-mid game and your jungler can help get your tanky teammates gold for their MR items(through snowballing lanes for kills/turrets or by just zoning the enemy laner away so your teammate can have less pressure while laning) then Diana won’t be a big problem.
Graves I can’t say that much about because I haven’t played him and I don’t pay attention to him that much when I do play with/against him. From what I have seen/heard he is a very aggressive early jungler so if you can counter jungle, counter gank or snowball from him if you catch him low in the jungle then you could have a relatively easy time snowballing and winning because he is pretty damn weak without an early advantage to snowball off of.