My favorite pokemon is Gastly, no doubt about it.
My favorite type are the Ghost and psychic types, because of their dark/misterious aspect (i just love those things qx)
Also, Jiglypuff(and its evolutions/involutions?) is one of my favorites, (is just too adorable to not notice ?)
Maybe i got others, like Wooper. Even when is not the stronger pokemon (at all)
But meh, Gastly and Jyflipuff more than any other.