To catch Lugia in "Pokémon LeafGreen," use a link cable or Game Boy Advance wireless adapter. With this, you can easily unlock the Mystery Gift feature of "Pokémon LeafGreen," obtaining a Mystic Ticket and capturing Lugia.
Obtain a link cable or Game Boy Advance wireless adapter
Computer and video game stores generally stock these items. Use either one of these items to connect with the greater Pokémon network of players.
Initiate the Mystery Gift feature in "Pokémon LeafGreen"
Initiate the Mystery Gift feature during standard gameplay once you are connected with your link cable. In "Pokémon LeafGreen," this is done by navigating to any PokeMart in the game. Once there, search for a sign on the wall next to the counter. Input "LINK TOGETHER WITH ALL" into the dialogue box that appears. A message box then appears, confirming that the feature has been initiated.
Attend a Nintendo event
Once this Mystery Gift feature has been activated, wait for a Nintendo event invitation. Nintendo events are offered sporadically and may require that you travel to a given location in "Pokémon LeafGreen." Only events that have a Wonder Spot at the location are viable locations for receiving Mystic Tickets.
Access the Mystery Gift feature near a Wonder Spot at a Nintendo event
Get your character near the Wonder Spot and initiate the Mystery Gift feature that was previously activated. Doing so unlocks the Mystic Ticket. The Mystic Ticket can then be obtained from the man located on the second floor of any PokeMart.
Use the Mystic Ticket to travel to Navel Island
The Mystic Ticket can then be used to purchase transportation to Navel Island, where Lugia is located. Travel to the port in Vermillion City and present the sailor there with the new Mystic Ticket. He then allows you to board the ship for Navel Island.
Discover the location of Lugia on Navel Island
Once on Navel Island, follow the lone path that enters the cave. Continue on until the path splits to the left and the right. Head down the right fork to locate the Pokémon Lugia.