Darkrai is a black, shadow-like Pokémon. It has a small head with a white fog-like ghostly plume billowing from its head covering one of its bright blue eyes, with the portion on its face resembling hair. It also has a red spiky growth around its neck. It has skinny arms and long black tatters hanging from its shoulders. It also has black, claw-like hands. It has the slight appearance of an hourglass figure and appears to be wearing an old, ripped cloak. It normally does not have any sort of legs, but it is able to extend stilt-like appendages in their place. In self-defense, Darkrai can retract its head and white "plume" into the pit atop its torso fringed by the aforementioned red growth.
Darkrai is known to "inhabit" dreams and causes the target to have unending nightmares, which can be stopped if exposed to a Lunar Wing from Cresselia. However, the "unleashing of nightmares" is actually a defense mechanism, instead of an intentionally malicious act. It can become a shadow and escape danger or contact with humans. It is also capable of some human speech. In The Rise of Darkrai, it was shown its power was weaker than that of Dialga and Palkia. As seen in an anime episode, Darkrai does not only cause nightmares; it is also attracted to them. It can also go around objects it is attracted to several times, as seen in the mentioned episode and Pokémon Ranger: Shadows of Almia. Darkrai possibly feeds off dreams, characterized by its association with never-ending nightmares. Darkrai is the only known Pokémon that learns Dark Void.
Darkrai made its main series debut in Sleepless In Pre-Battle!. Unlike the Darkrai in The Rise of Darkrai, this Darkrai was maliciously causing nightmares, much like in the games. According to Officer Jenny, it comes at a certain time every year. In the episode, however, it came earlier due to it being lured out by Team Rocket's machine, which was also causing nightmares. Cresselia is normally in the same place as Darkrai to stop it from giving nightmares, but due to Darkrai's early arrival, the people in Canalave City had nightmares for several days. One night, it was concealing itself when Cresselia used its abilities to reveal it from the darkness. The two then battled and Darkrai hid itself once more in the shadows.
In Phew for Mew, Sird let out a beam of light from a Poké Ball upon seeing Deoxys leaving for space. Thinking that Sird was trying to retrieve Deoxys, Red, Blue, Green, Yellow, and Silver tried to stop her, and Mewtwo charged into the light of the Poké Ball. Within moments, the five Pokédex Holders were turned into stone, and a black shadow appeared in front of Sird. When Sird reappeared in front of her Team Galactic colleagues in Double Trouble with Dialga and Palkia IV and explained what happened, the black shadow was revealed to be Darkrai, though Sird still did not reveal its name. Darkrai later reappeared in The Final Dimensional Duel VIII, where it was revealed that Sird had released it into the Distortion World. It first faced its arch-rival Cresselia. Charon later took control of the Pokémon, and, along with Giratina and Heatran, used it in a battle against the Sinnoh Legendary Pokémon in the climax of the chapter. Darkrai was later freed from the control of Charon, and departed to parts unknown.
A Pitch-Black Pokémon. It becomes active on nights of the new moon. This legendary Pokémon has the power to lull people to sleep and fill their heads with dreams. Proverbs say that Darkrai will make people have terrifying dreams on moonless nights. A Dark-type Pokémon, Darkrai uses the Dark Voidmove, along with Embargo, which stops foes from using held items.
Darkrai appears as a Poké Ball Pokémon. It puts fighters to sleep and damages them by using Dark Void.
NA: This Dark-type Pokémon can cause people and other Pokémon to experience nightmares. While it is floating in the air, it tucks its legs in so far, it looks like they vanish! In battle it will use a move called Dark Void, which sucks in surrounding opponents and puts them into a deep sleep.
PAl: A Pokémon shrouded in mystery, Darkrai has the ability to implant nightmares into the minds of both humans and Pokémon. It has legs, but seems to prefer to float in the air. Its favourite move in this game is Dark Void. When this attack hits something, it creates a vortex that sucks in fighters and puts them to sleep.
Pokémon Mystery Dungeon: Explorers of Time and Explorers of Darkness: Darkrai is revealed to be the main antagonist of the game in the post-game story. He wants to cover the world in darkness, and was behind the collapse of the Temporal Tower in the main storyline of the game. His interference is also the reason the player was separated from Grovyle and turned into a Pokémon. In the post-game story, he turns his attention to distorting the fabric of space to cover the world in darkness.
Sailor Eldritch's son says "Dar... Dark... Is watching me..." in his sleep before the player cures his nightmare. It is assumed that he is talking about Darkrai, as it is known to give its victims horrific nightmares.
If Darkrai was the cause of the sailor's son's nightmares, it can be assumed Darkrai is aware that the player cured the boy using Cresselia's Lunar Wing. When the player takes the Member Card to the Harbor Inn, the innkeeper (presumably an illusion created by Darkrai) states that he has been waiting for the player's arrival.
In the early Japanese versions of Diamond and Pearl, Darkrai can be caught with the Surf glitch. However, this glitch was fixed in other language versions. Another glitch has been discovered that allows players of other language releases to reach Darkrai without the Member Card.
This has been remedied in Pokémon Platinum, however, as Darkrai itself will not appear on the island without the event ticket.