You have to get the silver wing to the person near the mart in Pewter City then after a while go back in Johto fly to Olivine City go to the northeast whirl island enter it go ahead then go to the left until you will see a hole then enter it.....you will see a waterfall inside go ahead....then go inside a hole there not on the stair....enter it and you will see lugia there....Hint: bring many ultraball and use pokemon which lower the depense of lugia...then weaken it and catch it.......