Things You'll Need
Instructions
Go to any Pokemon Center and access the PC. Select one Pokemon that knows Flash and one that knows the Surf and Whirlpool moves.
Go to Olivine City on the west side of the Johto region. Stand next to the water and use the Surf move to start swimming.
Follow the path through the ocean. When you reach a whirlpool, press "A" to cross over it with the Whirlpool move.
Get out of the water when you reach a small island. Walk around the rocks and enter the cave. Use the Flash move to light up the room.
Walk east and then head north. Take the ladder to the next room.
Walk south and then turn left. Head south again and climb down the ladder.
Get in the water with the Surf move. Swim south and go down the waterfall.
Swim west and get out of the water. Go through the cave entrance.
Approach Lugia and press the "A" button to start the battle. Use your master ball to capture Lugia instantly or weaken the Pokemon and throw ultra or great balls until you catch it.