Answered
In Pokemon Diamond Pearl and Platinum
How do you get lunar wing?
After you gain the national dex (Beat the PKMN league champion Cynthia, see all the pokemon, then go to Prof. Rowan's lab and Prof. Oak will give you it) Go to Canalave city a…nd enter the Sailor's house. The small boy will be lying in bed. If you talk to his mother, she will say that he's suffering from nonending nightmares and is unable to wake up. Speak to the sailor at the docks and he will ask a favour of you. He will then take you tpo a place called Fullmoon island. When you get to the forest, there will be a crescent moon-shaped puddle and in the center, Crescellia will be waiting. Talk to it, It will be recorded in your pokedex, and will fly off, leaving the item you need - The lunar wing - where it was. Get the lunar wing and go back to the sailor's house. Giove the boy the lunar wing and he will wake up. You can now track down Crescellia on the marking map poketch app* and capture it. *When you get a certain amount of gym badges, go to the poketch company in Jubilife city and you'll get the app. (MORE)