I'm not going into what the Dark type is supposed to be. Its physical moves are about dirty fighting, but attacks like Dark Pulse and Dark Void are obviously attacks of concentrated pure evil. Houndoom is a hellhound. Darkrai brings endless nightmares. Hydreigon is a mythological monster, being a ****ing three headed grim reaping dragon has nothing to do with dirty fighting.
http://meta289.deviantart.com/#/d4j1eby Fact: Things are so much better when taken at face value.