Question

I have a shellder on deck for evolution

Answer 1

Castelia City (Answer Panpour), Driftveil City, Wellspring Cave(Dustcloud), Chargestone Cave (Dustcloud), Mistralton Cave(Dustcloud), Twist Mountain (Dustcloud), Challenger's Cave(Dustcloud), Victory Road (Dustcloud), Giant Chasm(Dustcloud) or in Black City. Hope this helps..

Answer 2

You need to go to any cave in the game, then you seek for swirling dust, there can be a pokemon, any of the type boosting gems, and also theres a chance of a evolution stone, I hope I helped :b