Gragas vs Yasuo

Let Barrel Roll (Q) charge before detonating it: damage and slow grow the longer it sits on the ground, and if you don't recast it, it explodes on its own.

Drink Drunken Rage (W) before engaging: drinking takes 1 second, then you take less damage and your next auto hits every nearby enemy.

Engage with Body Slam (E) through a path without minions: you stop on the first enemy you meet, and hitting reduces its cooldown.

After Body Slam (E), cast Explosive Cask (R) behind your target: the blast knocks enemies away from the impact, sending them toward your team.

Hit him with a cheap attack to trigger the Way of the Wanderer (passive) shield, then start the real trade: otherwise, it absorbs your best damage.

If you have projectiles, save them for after Wind Wall (W): it blocks them all for 4 seconds, on a 25 to 17 second cooldown. Other spells go through it.

Don't stand right behind your minions: each one gives him a target for Sweeping Blade (E), and he gets closer to you with every dash.

Get out of the line of his whirlwind, the third Steel Tempest (Q): without a knock-up, he can't cast Last Breath (R).

Judge his threat by his crit items more than his level: Way of the Wanderer (passive) raises his critical strike chance, so each crit item does more for him.