Been letting this question stew for a while, I’ve come up with some (in my opinion) nice Defoggers in Gen 8 UU.
Mandibuzz: Very nice mixed bulk, watch out for SR and rock-type hazard setters (hate you nihilego).
Flygon: RU by usage, but one of my favorites. Resistant to SR and immune to spikes/toxic spikes through levitate, can switch into fellow hazard-setters with ease. Obviously, watch out for ice-types and ice coverage.
Rotom-W: Most annoying out of all of these! Access to Defog, Taunt, and Will-O-Wisp is guaranteed to cripple most UU physical attackers. Honestly, my vote is to put this beast in OU.
Skarmory: Physically defensive wall. Slow as a rock going uphill, but access to many beneficial status moves such as Whirlwind, SR, Roost, Defog, and more. My defogger of
choice.
Hope I helped!