Does Vayne even have a weakness?

Late game?

Ultra mega burst. Good luck hitting her.

full ap sona late game or a veigar ult

Range and burst. Burst outranging her attacks is the ideal counter. (Example: fed for targeted burst, but be ready to cast the ult as soon as she's in range - if Vayne already ulted, run) (Example2: ; try to poke Vayne down but try not to hang around if Vayne ulted)

Also big AoE cc, the kind of AoE she can't Tumble out of. (Examples: , , ) (I actually countered a Vayne top with Galio some time ago... he can farm with Q and Vayne can't engage on him. And when my jungler came top... let's just say that 1 Condemn is not even close to being enough self-peeling in this case XD) (Explanation: Vayne can't poke a Galio with autoattacks, both because of range - Galio's Q can kill the minions without getting close - and because of the threat his ult poses to Vayne).

If you instead wanted an ADC that can duel Vayne, I'd suggest (blue build, keep your distance and wear her down with Q; you have to be able to aim his Q decently of course for this to work).

If I had to counterpick Vayne as an ADC, though, I'd take and just farm and Ult/W away if Vayne tried to do something (Tristana can't duel Vayne, but Vayne can't actually catch Tristana + Tristana is more useful in teamfights and sieges). (Assuming that Tristana's support is not a bloodthirsty blood knight and can understand the meaning of "please raka stop trying to engage that Thresh+Vayne duo, they might be slightly stronger than us 2v2")

Her players since most Vayne Mains are toxic AF.

vayne has some pretty clear weaknesses

pick a champion that can oneshot her with a single targeted button or pray she is braindead. But 99.9% of vayne players throw games so its fine.

She is mortal.

i like to play nunu against her when i support since they removed the attack speed reduction from exhaust