OK, this has been bugging and confusing me for a long time. No matter which way you look at it, even from the front, Darkrai has one eye visible. So does it have one eye or two?
Two.
It has a small head with a white fog-like ghostly substance billowing from its head covering one of its bright blue eyes...
http://bulbapedia.bulbagarden.net/wiki/Darkrai_(Pokémon)#Biology
