I could definitely go Vulpix hunting and seek a Drought ability, but I can't guarantee it. If the ability is only granted upon evolving with the Fire Stone, I could test them out and then proceed to trade you one that can be evolved with said Fire Stone. I personally am not fussy about abilities myself, but if drought is what you want, it can be done. Have you considered that it's the Hidden Ability, however, and not the primary one?
This all assumes I have a Fire Stone. I might have used mine. I'll have to rely on dust spots since I don't have a vibrant Black City.