description from dark pulse is "The user releases a horrible aura imbued with dark thoughts. It may also make the target flinch."
What makes a pokemon dark is it having the dark aura, which leads to it having the dark thoughts. You could think of it as being like possessed by a demon, but I dont think the dark aura is sentient per se in the way a demon would be. Its also comparable to mental i lllness.
This gives more reason why psychic and ghosts are disadvantaged against them. Both try to use aura but the dark type is essentially poisoning it. Imagine trying to read a dark types mind as a psychic, the dark thoughts are too strong.
Fairy otoh comes in and cleans up the aura (I think it would make more sense if fairy and dark were both supereffective against eachother, but whatever)
>>49874462whats the problem with that?
