So, what/who counters Twitch?

Anybody with an early game.

Deep and wide warding. The idea is to catch Twitch in vision before he would go invisible, not where he'd probably be invisible already. For example, instead of warding in either bush in the river, ward way past them within the river, in the enemy's Jungle, or wherever early in the path you think Twitch would come through.

lane bullies in teamfight, braum and yasuo and that's if your team has coordination to place themselves behind you

twitch has counterpicks twitch has no counterplay

twitch only form of counterplay is "win the game before 20 min" like any stat-checking carry

shaco

All in him Lv. 3 and two shot him. What is he gonna do? Stealth?

In terms of laning phase, he is bound to lose most of the matchups. Caitlyn is definitely the hardest one for him, followed by Xayah and Draven. When it comes to mid-late game fighting anything that can break him out of pace when he is ulting will do the work - Braum's shield, Yasuo's wall, turning invisible/invincible, activating Zhonyas, or some sort of big scale protection - karma's shield on mantra, janna's ult etc. He will feast on comps that cant do any of those things tremendously.

Not a whole lot counters him late game. You will need a champion who can dive on the backline and quickly disrupt him or a champion who can block his ult.

Perma Banning Twitch counters Twitch.

Anyone who can jump on him and cc him when he tries to stealth around a fight.

He can't survive being focused after 1 or 2 layered cc abilities. Not a champion-specific counter for him, just a general way to handle late-game problem champions that he is a part of.

for adcs or basically anyone who can play their carry aggressively and well. or basically any other hard hitting, aggressive support.

And like mentioned above, the walls: (though he can just wait them out or walk around yasuo's).

His early game is pure shit unless you're worse than shit or really passive. Shut him down early and that's mostly that, unless you wait for another 30-40 minutes.

Basically as "counterable" as your average Joe.

As a twitch player: Draven Caitlyn Lucian MF and imo kogmaw Zyra brand bard blitz lulu karma