Unlike other types, dark type can't be defined. It relies on an abstract concept of "evil" and even then, contradicts itself with pokemon like Absol and Darkrai, who are just misunderstood. And worse the one defining them are humans and not the pokemon themselves. So unlike water, grass or even fairy and psychic which all have a set of rules defined by pokemon themselves, dark relies on human judgement. So where exactly does dark type even come from? It should be removed and its pokemon added into other types.