Things You'll Need
Instructions
Mystery Gift
Go to any Nintendo event in which the "Mystic Ticket" will be offered. Check the official Pokemon website to locate the next event that will happen near your area.
Connect the wireless adapter to the transfer cable output connection at the top of your GameBoy Advance. Stand next to a "WonderSpot" machine. Turn the GameBoy Advance on and select the "Mystery Gift" option.
Download the "Mystic Ticket" from the event.
Go to Vermillion City and talk to the sailor. He will take you to Navel Rock where you can catch both Lugia and Ho-oh.
Trading
Connect the wireless adapter to the transfer cable output connection at the top of your GameBoy Advance.
Turn on the GameBoy Advance and select your save file. Go to any Pokemon Center and talk to the trade attendant at the back of the Pokemon Center. Make sure your partner does the same.
Select a Pokemon that you do not mind losing and select "Confirm" to initiate the trade. Your partner should select Lugia and select "Confirm." Once the trade is complete, you will have Lugia in your party.