Instructions
Capturing Ho-Oh
Walk to the house on Ecruteak City's northern side and enter; pass through its staircases and corridors, until you reach the entrance of Tin Tower. Stroll around the wooden barriers of the first floor to reach a set of stairs; go upstairs and continue down the next set of stairs.
Jump over the single ledge ahead, continuing left over the next two sets of ledges. Head right over one more ledge to reach the stairs. Go downstairs, jumping over the two ledges on the left and the single ledge to the south after arriving on the floor. Continue left to reach a set of stairs and walk north, hopping over a set of five ledges to another staircase. Cross the left side over two more ledges, walking south and then northeast over two more ledges. Go up the staircase.
Head northeast from the staircase to another ledge; jump over the two ledges on the right, continuing south one ledge, west two ledges, south five ledges and east two ledges until you reach another staircase. Cross a few steps east, north and west to a set of ledges on the next floor. Head south from the ledge and take the next staircase. Walk north from the stairs, heading southwest to reach a teleportation pad. Follow the path ahead to reach Ho-Oh and save your game.
Capturing Lugia
Fly to Olivine City or Cianwood City and walk toward the nearest body of water. Open your menu with the "Start" button and select "Pack" to find the item "Repel." Repel prevents low level wild Pokemon from initiating battle while you travel through any area susceptible to wild Pokemon. Use the HM, or Hidden Move, to surf at the water and travel south until you reach a whirlpool near a wall of rocks.
Approach the whirlpool for a message to use HM Whirlpool; press the "A" button to continue through the whirlpool, heading north and onto the nearest body of land. Walk around the cave to reach a small section of water. Surf across the nearby land to reach the other side toward the cave. Enter the dark cave, open your menu and use HM Flash to illuminate your way.
Walk north and then east to jump over a ledge; head north again and down a ladder. Travel southeast to another ladder and surf at the nearest body of water. Go south and then west until you reach another cave entrance; enter the cave and surf north to reach Lugia. Save your game and press "A" to initiate battle.