I am training its special attack and hp so I am currently training on the route to the left of hearthome city on bidoof for hp and ralts, budew, and roselia for special attack
For special attack, train on Gastly/Haunter in the old Chateau. For hp, try Valley Windworks cuz there are Bidoof and Shellos that are common here and they give off 1 hp ev.
I agree with swampert, but bidoof are common on route 201.