Why is Kommo-o in UU?

Question

Kommo-o can become an incredibly effective sweeper with Clangourous Soul. It can tank hits and deal out a good beating. It is versatile - it can be used as a tank, a special sweeper with Throat Spray, a physical sweeper, or a Stealth Rock setter. Any one of its 3 abilities are good, with all three offering immunities. It can counter its weakness, fairy types, most of which it will outspeed with 1 Clangourous Soul, with Poison Jab/Flash Cannon. Though it has a 4x weakness, some OU pseudo legendaries also do.
Some OU pokémon, such as Hawlucha and Pelipper, which is best used on a rain team, which is unreliable, have nothing like these capabilities. It is as versatile, if not more versatile, than Garchomp, which is in OU, and is just as good as dragonite.
It is also much better than most UU pokémon, so why is it in UU?

Comments

How is an "incredibly effective sweeper" shut down and KOd by Clefable and the Tapus, some of the most common Pokemon in OU?

+1 252 SpA Kommo-o Flash Cannon vs. 252 HP / 4 SpD Clefable: 238-280 (60.4 - 71%) -- guaranteed 2HKO after Leftovers recovery

0 SpA Clefable Moonblast vs. +1 0 HP / 4 SpD Kommo-o: 252-300 (86.5 - 103%) -- 93.8% chance to OHKO after 1 layer of Spikes

Where have you seen a Kommo-o run Flash Cannon or Poison Jab over Flamethrower, Boomburst, Drain Punch, Substitute, or Close Combat?

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Yes, it can be KOed by the tapus and clefable but it has the edge in speed after clangorous soul. Leading with kommo-o doesn't allow entry hazards to be set up against it and also allows it to build up stat boosts before encountering tapus, which aren't often used to lead. Poison jab, drain punch and ice punch work well together on a physical kommo-o so yes, poison jab can be used better than close combat. I wouldn't use substitute with clangorous soul, which is necessary, because of the HP loss. Also, don't Garchomp and dragonite suffer this  from ice attackers such as Garchomp and swampert.

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You'll probably get a better answer if you ask here: https://www.smogon.com/forums/threads/simple-questions-simple-answers-thread.3656259/

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Did you even see those calcs? If you would, you would not've pulled up the ******** "advantage in speed even though walls are super slow" argument

Answer 1

Here's a short answer to why Kommo-o wasn't used much in OU:
It is outclassed

I asked on Smogon, and a user named Katy said:

Kommo-o wasnt used enough as it faces stiff competition in all of its roles, there are better Stealth Rocks setters than Kommo-o like Landorus-T, occosionally Clefable, Ferrothorn, Garchomp, and Heatran. It also faces competition from Dragapult, Garchomp, Kyurem and Dragonite as main Dragons to use in the OU metagame. They all offer some unique traits already, which makes them more appealing for teams to use.
However, Kommo-os access to Clangerous Soul can make it an effective lategame cleaner once teams are weakened, as it gets a +1 in all of its stats and therefore can act as a pure physical or special sweeper or even as mixed versions. The best to run this Kommo-o set is on very offensive teams with some support such as dual screens, which can be given with Tapu Koko or Grimmsnarl.
Hope that helped :)

Source

Basically, it is outclassed in all of its roles, but you can utilize Clangorous Soul to make Kommo-o an effective late game cleaner in OU. Hope this helps.

Comments

Sounds like the old saying -- Jack of all trades, master of none