Darkrai is a wild Dark-type Pokémon that appeared in numerous movies.
The Rise of Darkrai
Years ago, Darkrai was found and saved by Alice's grandmother, Alicia. After she took care of him, she allowed him to stay in her garden with all of her Pokémon. Since then, Darkrai stayed with her and watched over her for many years. When Alicia grew older, she taught her granddaughter how to play her song, Oracion, meaning "prayer". Years later, Darkrai had been mistaken by other people, especially Baron Alberto, as an evil Pokémon wreaking havoc across town by putting various Pokémon to sleep as well as giving them nightmares. However, everyone has learned that Darkrai was trying to warn them about the upcoming dangers that could endanger the entire town. It was proven when Dialga and Palkia arrived and clashed with one another while both of them believed that they've invaded each others' dimensions. Only the Oracion can stop Dialga and Palkia's battle and soothe their fighting. While Ash and Dawn try to play the song in the Space-Time Tower, Darkrai tried to hold them off for as long as he could, but ended up putting his own life at risk when Dialga and Palkia's attacks killed him and eradicated him into nothingness. After Dialga and Palkia's deadly and intense fighting were finally stopped, Ash and Dawn asked Palkia to restore Alamos Town back to its original dimension thus restoring Darkrai back to life.
Arceus and the Jewel of Life
Darkrai made its second appearance in the Arceus and the Jewel of Life during the ending credits.