The Lunar Duo is a duo consisting of a Legendary Pokémon, Cresselia, and a Mythical Pokémon, Darkrai. They were introduced in Generation IV and are native to the Sinnoh region.
Members
| Pokédex number | Image | Pokémon | Type |
|---|---|---|---|
| 0488 | 
|
Cresselia | Psychic |
| 0491 | 
|
Darkrai | Dark |
Description
Both Cresselia and Darkrai are associated with a different phase of the moon, with Cresselia being based on a crescent moon and Darkrai on a new moon.
The Abilities they both possess cause disruptions to people and Pokémon for their sleeping is disturbed from both sweet dreams and worst nightmares. Hunted for their misfortunes, forces the two Pokémon to be forever separated except for once a year when their abilities are suppressed the Alpha Pokémon Arceus so that both Pokémon can be given a single night together.
The feelings between the two Pokémon are also most likely based on a Chinese folktale, The Cowherd and the Weaver Girl based on the brightest two stars in the known universe, Altair and Vega. The Cowherder and The Weaver Girl's love was forbidden and were banished on opposite sides of the celestial river of the Milky Way. But once a year, on the seventh day of the seventh month all the magpies in the world fly up and build a bridge between them so the two lovers can be united for a single day of passion.
Appearances
Core series
In Pokémon Diamond Version and Pokémon Pearl Version and Pokémon Platinum Version, Cresselia can be found on Fullmoon Island after defeating the Elite Four, after the player secures a Lunar Wing for Eldrich's son, who is suffering from endless nightmares. Meanwhile, Darkrai can be encountered only through having a specific event item, the Member Card, to go to Newmoon Island. In Cresselia's case, the Legendary Pokémon disappears but leaves behind a Lunar Wing before starting to roam around the Sinnoh region.
Anime
In the anime, Darkrai leads Cresselia, with Darkrai stopping only to cause Bad Dreams and Cresselia scaring it off and healing anyone in the vicinity with its Lunar Wing. Both appear in "Sleepless in Pre-Battle!".
Darkrai is the Pokémon of the New Moon and resides on Newmoon Island while Cresselia is the Pokémon of the Crescent Moon and resides on Fullmoon Island.