I'm an actual psychic and I'm SICK and TIRED of GF misrepresenting my type in their games. We are FAR more capable of dealing with ghosts than the average person, so I'd say that psychic types should be immune to ghost type attacks and psychic type attacks should be super-effective against ghosts. Psychic being weak to dark also doesn't make sense, because after my psychic awakening, I began to see my surroundings clearly even in complete darkness. Considering how many psychics attention-whore by bending spoons, psychic type attacks should be super-effective against steel. The only type which should resist psychic is psychic itself, considering only psychics can block psychic attacks.
That being said, the bug type and every single bug type Pokemon should be removed from the games because they are DISGUSTING.