ahh I'm sorry I meant Slowpoke >_<
And unfortunately I need it for Sun/Moon (you can only get it post-game)
I see. I'd help if I could, but my copy hasn't arrived yet. Hopefully someone else can trade you what you are looking for ^^
Otherwise, King's Rock can apparently be found on wild Poliwhirl, Poliwrath, Slowbro, Politoed, and Hariyama. Maybe you could acquire one this way.