That's the thing, 67% of the battlers on Shoddy and (soon to be) Wifi are smart.
Of course, won't the smart battler use something to fuck over Skymin's few fears? With Scizor packing Bullet Punch, ScarfGar, Weavile, Deoxys-S Mamoswine, etc. won't be much to worry about. After that, Skymin can proceed to rape the other team. Registell needs a more SpDef distribution than one thinks. A Life Orb'd Seed Flare and Earth Power actually have a chance of 2KOing the standard OU tank set if I'm correct :/. Regice is one counter I can name off of the top of my head since Seed Flare 3-4KOs. Speaking of, Seed Flare has an 80% chance of that SpDef drop while Air Slash has a 60% chance of a flinch, this means that Seed Flare is a STAB, 120 BP move that doubles each turn if it disregards the 20% of no Special Defense drop :/. It's like Stone Edge hitting twice in a row, a large chance with a huge payoff.
When Garchomp was OU, everyone who used it had a way to rape its potential counters. making a clean sweep possible. Scizor and Suicune/Tentacruel can just about cover Skymin's potential counters.