Pokémon Sleep announced during the Pokémon Day 2025 broadcast that a Cresselia VS Darkrai event will be coming to the game in March 2025. Darkrai approaches with a nightmare, but Cresselia is ready to transform everyone's Drowsy Power into strength to fight back!

YouTube Clip - Cresselia vs Darkrai in Pokémon Sleep!

Source: https://www.youtube.com/watch?v=k5Ga-meZ1Pk

Event Notice: Cresselia vs. Darkrai

Beginning around the end of March 2025, we will hold an event—Cresselia vs. Darkrai! Both Cresselia and Darkrai will appear in this event!

Psychic-type helper Pokémon will be particularly effective during this event, so we recommend raising your Psychic-type helper Pokémon to get ready! Psychic-type helper Pokémon include Mr. Mime, Espeon, Wobbuffet, Ralts, Kirlia, Gardevoir, Wynaut, and Mime Jr.

More details about the Legendary Pokémon Cresselia, the Mythical Pokémon Darkrai, and the event are coming in a later update. We hope you’re looking forward to this event!

Source: https://www.pokemonsleep.net/en/news/323337333335313531373738393838303333/