Psychic-type Pokemon are weak to Dark, Bug, and Ghost-types. The reason for this is due to the fact that Psychic-types deal with the mind and Dark, Bug, and Ghost-types are 3 very common fears most people can associate with. - It all makes sense now.
Slowpoke - 079 - It is always vacantly lost in thought, but no one knows what it is thinking about. It is good at fishing with its tail. It lazes vacantly near water. If something bites its tail, it won't even notice for a whole day.