The ONLY reason Yasuo is broken
is because for some reason, you allow his ultimate to trigger off of other champions displacements. Why? As a standalone champion Yasuo is very well balanced. But you take it 8 steps farther and give him literally INSANE synergy with so many champions, that allows for premades to just abuse the champion to a completely stupid degree.
you would literally shut up every QQ Yasuo thread if u just took away the fact that he can ult off of his teammates displacements. He would still be a solid champion. One that isn't rewarded by default winning the game because Nami has a Tidal Wave, or Ornn has his ultimate, or Orianna has a command, or Alistar has pulverize, or Wukong has Cyclone. etc etc etc.
Yasuo is a good champion, I don't see the reason of giving him default win- levels of synergy.