you go talk to the sailor in cancalve city, then you go into his house.his son will be murmuring something. then you go back outside and the sailor, if you talk to him again will take you to fullmoon island to get the lunar wing. when you walk into the trees you will see cresselia. it runs away and gets registered on your pokedex. then you go back to cancalve and talk to the sailors boy. he will awake and that is where you check the pokeapp that tells you where cresselia is. go to snowpoint city and go into the temple where you can find a golbat with mean look. and later in the temple when you have all 3 reggies in your party, you can find reggigigas where the statue is.go to a place in sinnoh that has a space where if you walk 1 step, you will be in the next area. keep going back and forth untill you find cresselia. and when you throw a pokeball, use the ababababababababababababababababababab technique it works mostly.