Need Help Dealing with These Champs

Seems very tanky and fast-moving with high damage from very early in the game. He shreds me when I play tanks, and he bursts me when I play mages. what champs have an easy time against him, and what are his weaknesses that I can exploit playing any champ?

Pokes me out of lane, chases to turret, wins trades. Any advice helpful.

Ditto Xin. Seems to do pretty ridiculous levels of damage for how hard she is to kill. What ruins a Vi's day?

You can't run from her. You can't chase her. You can't out-sustain her. And she seems to do really high burst damage. She decides if she lives or dies, and there's very little you can do about it if she engages and disengages properly. Advice welcome.

Ditto Rek'sai. His damage is really high while building tanky/bruiser, and you can't kite him. What do you do?

He doesn't give me trouble in lane, like, ever. But it doesn't matter if he's denied in lane because he gets free AP and will always get fed in team fights. Even if he's behind, he can punish you for buying AP. Veigar players say you should counterbuild against him, but stacking MR against a team with heavy AD threats seems like a catch 22.

Another champ that's not that hard to shut down in lane. But he always seems to get big off of minions and becomes hard to catch, hard to run from, and the range and damage on his Q becomes insane. It seems like you basically have to dedicate 2 teammates to sit on him all game to shut down his minion farming before he spirals out of control. Advice?