Okay, maybe Akali needs something to get to viability. But that's it.
Kat is a little on the weak side, but is pretty decent throughout the game.
Zed is pretty good right now, I'd wait to buff him until marksman changes are done. BoRK might be getting changes.
Talon is a good snowball champion.
Diana is still a decent enough champion. I like her in the jungle.
Ekko was almost brought into Worlds as the standard safe mid laner, he has one low CD spell that wipes out a creep wave.
LeBlanc isn't that bad. She still has the ability to burst things away and can still escape from sticky situations. I don't really see what made her that much weaker.
Actually, I find Fizz on the weaker side, since he has shit waveclear and has no defense in lane (other than a lowering of basic attacks, which means nothing in mid) against most ranged mages. His only real chance to win lane is to all-in at Level 6 just as he gets ult, and hope he's at full health at that point. I guess he makes up for it with his late game, but he's still not that great.
Yasuo has a really good kit. I agree with you there.