How do you counter a yi as an adc

Proper positioning

wellllll... you have rakan spam DANGER pings.

then you pop your youmuus and hopefully by this point in the game you've bought

it also helps to have

Yi is a melee adc (at least in how he builds). Since he is melee, he should have the advantage in destroying adcs once he gets in melee range. It would be pretty fucked up if a ranged champion can duel Yi at melee range, that is if they have the same amount of gold. Not to mention, it is his job to annihilate adcs late game. The only way to stop him is relying on your team, such as your support and tank, who hopefully are carrying some hard cc. Since he is melee, and has a conditional resettable gap closer, his team fight in general is weaker than an actual adc, who is ranged. Late game, range = safety, less risk, higher survivability and overall better carrying potential. Most melee champions who have limited gap closers fall off, since they become rather kiteable. Yi is melee, so he can somewhat be punished with range, but of course he can be quite dodgy and slippery if not managed well. On the other hand, Yasuo generally has a better team fight for a melee adc champ, as he has multiple gap closers with an AOE hard CC ultimate that can win you team fights. Of course, Yasuo's set up is a lot harder than Yi's if he doesn't have an aoe knock up from his allies, but potentially more rewarding.

pick vayne, build crit and kill him in 3 auto attacks

You don't lmao He counters you

You don't, you have to hope the rest of your team has the tools and capacity to deal with him.

Y ask for the team for peel and git gud

Have an ally cc him or exhaust him.

You don't.

Draft CC in other roles then you won't have an issue.