#002. Long ago, Darkrai tried to create dreams, but they came out as nightmares. Because of that, he fell into despair, only creating more and more nightmares until they spread across the world. Only Cresselia was able to calm Darkrai, even having to attack him in order to achieve that end, but Arceus noticed after some time. He relinquished both of their titles as dream and nightmare guardians, and banished them both to their own islands north of Canalave City.
Mew tried to fill in the gap since Cresselia and Darkrai could no longer create dreams and nightmares, but this task soon took its toll on Mew; she created munna and musharna, designating them as the "true" dream guardians to spread dreams of all kinds across the entire world.
uUnfortunately, the absence of dreams left humans without dream symbols to provide moral guidance. The "days without dreams" are considered a factor that led to the Unovan and Kalosian wars.
Thus, Darkrai went down in history as a hated pokémon, never being portrayed in a favorable light since. (@shydows)
