>>37153283Darkrai had the Cresselia side quest in D/P/Pt where you go to fullmoon island to retrieve the lunar wing in order to wake up the boy that fell into an endless nightmare. He even whispers Darkrai in his sleep.
Then when it comes to obtaining Darkrai you actually have to catch it by going to newmoon island that's only accessible if you use the event item to check into the harbour inn in Canalave City.
It feels like they put more effort into this event than they did for almost every legendary outside of the cover ones in gen 6-7
