So, I'm gonna go ahead and throw my hat in the ring for this. I think Yasuo is dumb and needs to be less... well, painful to play against. The amount of times Yasuo has single offhandedly won a game because he picked Yasuo is... well, stupid. Really stupid. It doesn't feel like a skill-lane match up against him, it feels like "I'm either going to get murdered earlygame, or I'm going to murder him but he'll still be relevant because he has ridiculous damage, utility, and teamfight potential whether he's fed or not."
I'mma put this here to stop people from bein' butthurt about walltext, because that's whats about to go down. also inb4 butthurt yasuo mains defending their overloaded champ.

TL;DR- Yasuo is overloaded AF and very annoying/unfair to play against unless your entire team has point-click CC and/or the rest of his team does nothing. I'm surprised Riot hasn't Olaf'd him yet with how dumb everything is. He's not OP, he's just annoying and unfair to deal with.
Right. With that out of the way, lets begin;
I'mma list out his abilities and passive, I'm gonna say whats stupid about 'em and what's nice about them and how I would fix them.
- PASSIVE
Yasuo's critical strike chance is doubled, but his critical strikes deal 90% damage, reduced to 75% damage on Steel Tempest.
Resolve: Yasuo generates 1% of his maximum Flow for every 59 / 52 / 46 units he travels by any means, requiring a total of 5900 / 5200 / 4600 units traveled to obtain maximum Flow. At maximum Flow, the next instance of champion or monster damage against Yasuo consumes all of his Flow and shields him for 100- 510 (based on level) damage for up to 1 second.
Already there's something wrong here. The obvious part is that there are two passives in the place of one. Who else does that? No one, because that's fuckin' stupid. Most people who have more than one passive [Varus, Vayne, Tahm even who is also an annoyance] have them on abilities, not packed into the same ability and available from the beginning of the game. What else is stupid is the fact that he has a shield in his sort of playstyle. Yasuo, as is, has this weird mix of fighter and assassin in his kit. Fighter, because he builds a little beefy on occasion [trinity force, cleaver, sometimes other things], assassin because jesus christ thats a lot of damage with very little counterplay. I know he isn't an assassin, but his damage is on the level of one, even without items.
Anyway, the way you're supposed to beat a fighter in lane is to poke him down, right? Well, Yasuo says no. Yasuo says "here's a shield that can take your harass for when you CAN hit me." Not that big a deal by itself, Malph has a shield that just comes back every so often, its even stronger. But Malph doesn't have the same kit as Yas. Yeah, you can autoattack Yas to get rid of his sheild, and if he's smart he will either;
- All in you and win the trade, which he has ample room to do. He has the damage, he has the cc, he has the ability to say "nah" to things you do, and he has means of escape.
- E away. Literally, E away. All he needs to do. Maybe even whip up a W in case there's something coming after him.
Outside of being a fighter, he's also able (and is intended) to go glass cannon melee ADC, which this shield ALSO DOES NOT FIT WITH, because its counter-intuitive to the glass part of the glass cannon/
Now, how would I fix this? Remove it. Just... just... there it goes. Give him something more fitting to a fighter/melee ADC role, like maybe ramping crit chance or ramping armor pen, or split this ability with his Q. I'll talk about that next. This shield doesn't fly and is very toxic to play against with playstyles like his.
TL;DR - Yasuo's passive is dumb. Remove it and/or rework it. Absolutely launch that shield into the sun because it doesn't belong on him and only makes him more infuriating to deal with.
- Q
Active: Yasuo thrusts his sword forward, dealing physical damage to all enemies in a line. Steel Tempest can critically strike and will apply on-hit effects to the first enemy hit.
Physical Damage: 20 / 40 / 60 / 80 / 100 (+ 100% AD)
Hitting an enemy grants Gathering Storm for 10 seconds. At 2 stacks, Yasuo's next Steel Tempest is empowered and will consume all stacks.
Empowered Steel Tempest
Empowered: Steel Tempest unleashes a whirlwind that travels an extended distance, dealing the same damage and knocking airborne all enemies hit.
Yasuo can cast Steel Tempest during Sweeping Blade to change the area of effect a to circle about him, which does not benefit from Empowered's extended range. The cooldown and cast time of Steel Tempest is reduced by 「 0.6% for every 1% bonus attack speed 」, down to a maximum 66% reduction.
This is a rather overloaded ability that counts practically as a second, longer ranged (albeit slightly) autoattack. It's used as such, and I think that's kind of neat. The whole cooldown reduction from attack speed is pretty neat too. And yes, the tornado thing is kinda cool. But like... jesus, could you fit any more abilities into a champion? I feel like Riot flipped a coin to decide on what his Q should be and it landed on the edge.
How would I fix this? Split the ability. Either make it to where his autoattacks build up the stacks of gathering storm and his Q turns into the tornado, or his Q stays as the second-auto like ability and the tornado is moved to another ability entirely. Also, the tornado should not apply onhits. that's super dumb. OH AND THAT SPINNY BULLSHIT. No. Nononono. None of that. It should either not knock up [congrats, you took the skill out of a skillshot], or... well, not exist. There's no counterplay to that. He charges up 3 stacks, dashes onto you, knocks you up, ults, either kills you or leaves you crippled, then dashes away back to his minions.
TL:DR- Yasuo's Q is dumb. It's overloaded and it's synergy with the rest of his kit sets up gaps to weaknesses that should be exposed.
- W
Yasuo creates a gust of wind that travels forward to form a wall in front of him. The wall slowly drifts forward 50 units over 3.75 seconds, blocking all enemy projectiles with the exception of turret attacks.
Free projectile blocking on a decently low cooldown. [18 at max rank, 0% CDR. btw.] 'nuff said.
How would I fix this; Remove it. Does not fit with his kit, is not fun to play against. Braum has a shield because he's a protector. Yasuo is a lone wolf. It's almost like someone at riot was like "HEY YOU KNOW WHAT WOULD PISS OFF LITERALLY ANYONE WHO CAN FIGHT YASUO? IF THEY COULDN'T." if you insist on it staying, it needs to have a health bar. It's just "Nope, anyone on your team who has projectiles that can't get behind this is useless for the next 3 and three fourths seconds. Go ahead and cross this line into my melee/knockup range. I dare you."
spoilers, if you do that, you'll die.
TL;DR- Yasuo's W should not exist. Next.
- E
Yasuo dashes a fixed distance in the direction of the target enemy, dealing magic damage and marking them briefly. The speed of the dash scales with Yasuo's bonus movement speed.
「 Magic Damage: 70 / 90 / 110 / 130 / 150 」 (+ 60% AP)
Each cast increases the next dash's base damage by 25% for 5 seconds, up to 50% bonus damage.
「 Bonus Damage: 17.5 / 22.5 / 27.5 / 32.5 / 37.5 」
Yasuo cannot use Sweeping Blade on a marked enemy.
Ah yes. Yasuo dashes from minion to minion, to you, Qs, then dashes back to safety. Also easy lasthitting [BECAUSE HE NEEDED AN EASIER TIME IN LANE RIGHT]. They think near infinite dashes having a cooldown on a target is a good enough excuse for it to have nearly no cooldown. At max rank, its .1 second. That... thats pretty gross. That's unheard of mobility that charges his shield and does damage. How did this make it past testing without someone going "Hey, that might be a little bit stupid."?
How would I fix this? Irelia Q it. Only resets if it kills a minion. Give it an actual cooldown otherwise. That is literally all that needs to be done. It would be so much healthier if he had any actual risk to make up for his mobility potential. The only way to actually catch a yasuo is to have like twelve Tarics glue themselves to him and hope his windwall is on cooldown AND that he doesn't have any movement speed built.
TL;DR- Yasuo's E is a stupid dash that might as well be a manaless targeted Kassadin ult.
- R
Yasuo blinks to the nearest visible Airborne icon airborne enemy champion to the cursor, instantly generating maximum Flow. Upon arriving, he suspends all nearby Airborne enemies for 1 second and deals them physical damage.
Physical Damage: 200 / 300 / 400 (+ 150% bonus AD)
For the next 15 seconds, Yasuo ignores 50% of his targets' bonus armor. Casting Last Breath clears all stacks of Gathering Storm.
And the grand finale; 'You thought you were fucked before'. I actually think this is really cool. What I DON'T think is really cool however is how ridiculous the range is and how you can hit an entire team with it, provided they're all knocked up by some force. The suspend is pretty cool, the armor pen is alright, the damage is on ultimate levels. Nearly everything checks out with the power balance, but then you add it to his kit and it just... hurts. It's too easy to get this ultimate move off, It's not even point and click. You press R. It's Karthus levels of Lazy. You don't even have to be the one who knocked them up, and they don't even have to be close together. The enemy doesn't even have to be classified as knocked up, just displaced by like say, Draven's E.
How would I balance this; Decrease the range, make it targeted (NOT INSTANT-BLINK CAST) and AOE, only affecting the enemies in the AOE. Alternatively, make it a dash-skillshot that knocks up enemies in the path and suspends them, leading to the usual ult things.
TL;DR- Yasuo's ult is surprisingly the least stupid part of his kit, but that isn't saying much. It's range is ridiculous for what it does and it needs to be reworked to include less 'press r to win' and more 'use brain to win'.
TL;DR TL;DR- Yasuo is a fair and balanced champion that requires skill to play[/s]. Riot needs to make him more skill-intensive. I ran out of letters. help.