Yasuo is a champion that is very mobile and does a lot of damage but is very squishy. Yasuo is classified as a Slayer, mobile squishy champions with high damage. Yasuo is a hard champion to master. Easy to play but hard to master. Yasuo is very fun to play. Many players assume that you just dash all around the place, but it's different from that. You need to choose which minions to dash through since they will have a 6-10(depending on level of Sweeping Blade) second timer when you dash through them. Yasuo is fun because his kit is unique and you can make big plays with it if used correctly. Yasuo is mostly physical damage. The lower, magic damage is from your E (Sweeping Blade). If you like making big plays and you also like edgy sh*t, then Yasuo is for you.

Pros

-Very strong early game and late game
-Snowballs hard with items
-High offensive abilities (ATK SPD, Critical, ATK DMG, etc.)
-Very mobile when minions are present
-Short ability cooldowns

Cons

-Very prone to crowd control
-Hard to master
-Very squishy

Passive(Way of the Wanderer): Doubles Yasuo's critical strike chance. However, his critical strikes only deal 90% damage. While moving, Yasuo gains Flow. At 100% Flow, Yasuo will gain a shield that absorbs damage anytime he is attacked by monsters or Champions.
-Flow is replenished faster the more movement speed Yasuo has.
-Flow can be replenished by Flashing, Teleporting, or using Yasuo's E (Sweeping Blade).

Q(Steel Tempest): Yasuo will thrust his sword forward in a straight line. Hitting an enemy will grant one stack of Gathering Storm that lasts 10 seconds. Getting one more stack of Gathering Storm will empower your next Steel Tempest, launching a whirlwind that knocks up all enemies in a line (the whirlwind does the same damage). Casting Steel Tempest in the middle of Sweeping Blade will make Steel Tempest cast as a circle instead of a line.
-CD lowered by Attack Speed. (Lowest cooldown is 1.33 seconds)
-Applies on-hit effects on the first enemy hit and will count as a basic attack on the first enemy hit.

W(Wind Wall): Sends out a slow-moving wall of wind that blocks any projectile that comes into contact with the Wind Wall.
-Will not block lasers like Lux's ultimate and Vel'Koz's ultimate.
-Will not block turret shots.

E(Sweeping Blade): Dashes to an enemy dealing magic damage. Each successful Sweeping Blade will deal 25% more damage up to 50%. Dash has a FIXED range. Enemies you dash through will be marked for 6-10 seconds (depending on the level of Sweeping Blade) that says you cannot dash through them again.
-Can be stopped by crowd control.
-Can dash through terrain if used correctly.
-Fills up Yasuo's Flow bar.

R(Last Breath): Blinks to any airborne enemy while gaining maximum Flow, suspending them for 1 second dealing physical damage. Afterwards, Yasuo's critical strikes gain 50% Armor Penetration.
-Will reset all stacks of Gathering Storm.
-Yasuo is still prone to attacks and CC while casting.
-Yasuo can use Last Breath on multiple enemies.
-Yasuo will try to use Last Breath out of enemy turret range if enemy is in enemy turret range.

Yasuo can synergize with many champions. Mostly champions that are able to airborne. Champions like Orianna, Malphite, or Cho'Gath are great with Yasuo. They all have AOE knockups which can allow you to multiple-man ultimate.

Yasuo also needs teammates (like all champions) since he goes down very easily. Yasuo does best when someone else goes in first and you follow up from behind. Staying on the frontline during team fights is very dangerous. Play Video

There are many different combos you can use with Yasuo. One of the easiest to perform and the coolest looking is the E+Q+Flash. It is where you dash with Yasuo's Sweeping Blade and use your 3rd Steel Tempest and flash right after you press Q. Load up your 3rd Steel Tempest stack (the tornado). Then E though something (preferably a minion), and use your Steel Tempest. RIGHT AFTER you press Q, flash to your enemy to knock them up. This requires timing and knowledge of your Flash range. Play Video
Another unique trick to do is the Q Cancel. This is where you can cancel your Steel Tempest's animation. There are common ways to do it. Using Wind Wall and using Flash.
The Wind Wall Way: You can Wind Wall (anywhere) and press Q to Steel Tempest but your Steel Tempest Animation will be hidden due to casting Wind Wall.

The Flash Way: You can Steel Tempest and right after, press flash. Play Video

Yasuo's farming phase is very good. He can last hit with his Q from far range in case the enemy wants to bully you. Since Yasuo is very offensive and his Q is AOE, he can easily clear up minion waves at higher levels.