There's no reason to use skarm lol. The main reason it's a dogshit mon is because of the fact that it's a defensive steel that can't actually check any of the psychics in the tier (m-zam, lele, mega lati@s, medi), and is extremely passive in comparison to its competition. None of the aforementioned strengths matter that much when skarm is strapped for moveslots, and can't fit all of its "strengths" all at once(it needs roost/whirlwind/defog/spikes/toxic/counter/bb to actually be a functional pokemon).