So its very difficult to not get frustrated at certain champs, some may just counter you or your playstyle, but I can at least give advice on how to face them if that helps?
: pick a mage or long range champion that has some mobility (ahri, lucian) or pick malzahar cause of R. Poke her out early and then just be careful after 6. Pre-6 is your window to dumpster her, but sadly cant get too close cause her dps at close range is still high early.
: freeze lane and hard poke, he literally cannot do anything to hurt you pre 3, pick a range that can auto, or use hit and run tactics like ekko can. By the time he hits 3 he will be basically useless compared to you either in minion gold or exp. Be careful at level 6 but you should have magic resist items by the time he is level 6.
: weak to hard cc, like REALLY WEAK to hard cc. Use that against her. Gragas destroys kat
: Shes just really strong right now, at most you can all in her but that's not really an option due to items like zhonya's and oriana's ability to shield herself, so I suggest roam a lot.
: Yasuo is weak to champions that do lots of burst and can get out fast, so try ekko, ahri, or leblanc against him. Also ninja tabi just destroys his overall damage if you are having extra difficulty.
: viktor can be destroyed by those who can all in but also have range, my personal favorite against him is jayce, try that out. If the viktor goes tank make sure to rush penetration items such as last wisperer or lethality items.
: Despite her E countering mobility, you want to have a mobile champ against her, ekko can sidestep her Q to mitigate some of the damage, and can also dodge her w to avoid her one-shot combo. After she E and W she only has Q to rely on, so go in then.
: honestly I got nothing, this champ is really basic which in turn makes him semi broken, all I can suggest is pick a champ that can rush qss or pick a champ that can rush adaptive helm. Otherwise, You can pick a champion with a spell shield such as siver and nocturne who can block his r. Otherwise just focus on getting rid of his little voidlings in lane, without those his push power is mediocre at best.
: Shes honestly just strong and is very reliable, the only real way to beat her is to dodge her Q's or just be fed. Qss helps a little too.
: He is oppressive and will go for turret, so don't let him do that, take a champ that can all in and scare him. (ekko, yasuo)
: Pick literally any mage and rush Zhonya's, you literally take away his ultimate ability for free just by using it properly. Not to mention his damage compared to other champions is relatively low due to his higher mobility. You should have a fine time against him. If you aren't a mage you are still basically stronger than him due to him being VERY weak right now. Just rush something like guardian angel or get some HP. Also stay behind minion waves at all times, his Q damage is reduced if it hits a minion first.
: She is honestly just a really strong champion due to polymorph and her ultimate, so I suggest just banning her if she becomes too much trouble.
: play a ranged champion that can outrange his turrets, if you pick first and you aren't a range champion go dorans shield an no matter what get resolve as either primary or secondary rune tree for second wind. Second wind destroys his poke based kit.
: all in. Just all in the guy or hard cc him. He is very reliant on his stars for damage and is honestly relatively weak. If you are ahead you also need to put constant pressure on his turret so he is unable to roam, which is his strongsuit. Also don't roam to follow him unless you are predicting where he is going to be or unless you have teleport. The best option in that situation is to just push tower as hard as possible, make him lose cs, and get turret plating.