With metagross sticking around as it is, expect to see slowking around a lot. turns out, it's actually an incredibly useful pokemon that, while not filling the role of slowbro is incredibly effective nonetheless. Thanks to it resisting 3/4 of metagross's attacks and being too bulky for grass knot, it takes on metagross extremely well. It also checks pokemon like keldeo and heatran quite well. It's viable as a normal set, with scald/psyshock/twave/slack off, as well as an incredibly cool AV set. The AV actually has incredibly utility in OU, checking strong wallbreakers such as Zard y and Lando I.
252 SpA Life Orb Sheer Force Landorus Earth Power vs. 248 HP / 96 SpD Assault Vest Slowking: 129-152 (32.8 - 38.6%) -- 98.9% chance to 3HKO
252 SpA Mega Charizard Y Solar Beam vs. 248 HP / 96+ SpD Assault Vest Slowking: 156-184 (39.6 - 46.8%) -- guaranteed 3HKO
it's no passive slouch, with power gem OHKOing zard y and scald nearly OHKOing lando i, not regarding a burn or if you have ice beam. it's not set up fodder either, learning dragon tail to phase potential set up sweepers like subdd gyarados. it's important to note azu and altaria still use you as set up fodder because of fairy typing. with mega meta here to stay, slowking definitely has a chance to earn a teamslot on balance teams.