After Testing, I found Yasuo's counter :v

Dunno what it is about this guy's W shield, but it really hurts yasuo if he engages, his taunt when yasuo has his wind passive up can cause him to use it and not follow up with his ult, the passive increases damage with armor build which also hurts yasuo.
Did random testing, had friends test it in casual and ranked. Total of 35 testings.
won = 28
won = 7
Builds varied.
. Long AA range to take down shield, wait out his windwall, bam Tibbers unloaded on him and dead. Or if she's banned I go for Diana as she can outduel him and has survivability with her shield.
. If Yasuo gets botrk and duels him, he'll win with his ult, his lifesteal and warlord's bloodlust, which is very common on him. Not to mention him buying resistances or
which gives mr, more lifesteal and qss (I buy it a lot on Yasuo).
If Yasuo's team is full ad, then yes it's an easy win for Rammus.
Also Rammus is a pain in the ass for Yasuo in the early game, especially if his enemy laner and the jungler are premades.
he is also really good, w and q punish melees hard and his e can pop his shield from range, if he ults you with your w active hes gonna take some good damage
Mercs and Hexdrinker, he can 1v1 Morde very easily, since he scales better than Morde imo.
gg
or
. Maybe late game, but still.
you think you can fight? ILL SHOW YOU HOW TO FIGHT.