Lugia is an immense, draconian mythical Pokémon with avian qualities. It has silver-white feathers over most of its body, except for its blue underbelly. Lugia has ten fins running along its back, which stand upward while flying, but lie flat on its back in the water and on land. The fins are used as rudders for steering in the air and are flattened in the water to reduce resistance. It has two powerful rear legs with three-toed feet, and two wings with large, finger-like feathers, giving the appearance of hands. Its eyes are masked with two dark blue fins, and two similar spikes are at the end of its long tail. Lugia's head tapers to a point and it has a serrated beak which bears similarities to a dragon's maw. It may be inspired by the Wyvern, a mythical draconic creature that stands on two legs, wings that function as hands and often has a barbed tail. Its child Silver is unfortunately not in the games but appears in the anime.
Lugia has the ability Pressure, which causes the opposing Pokémon to double its PP usage in battle.
Known as the Guardian of the Seas, Lugia is tremendously intelligent and is very gentle with the life around it, despite his colossal size. Due to the fact that it can blow houses away with the single flap of its wings, it isolates itself deep within the great current, to prevent it from harming civilization. Lugia is also intelligent enough to even speak telepathically, like Mewtwo. It can gracefully fly through the skies and can sometimes resemble a bird. It is closely related to Ho-Oh, considered to be its rival or polar opposite, as Ho-Oh is the Guardian of the Skies. The two once both resided in Ecruteak City atop the Tin and Brass Towers and worshiped by humans until the Brass Tower burnt to the ground and both birds flew away. Lugia and Ho-Oh are the mascots of Pokémon Gold and Silver, and the remakes HeartGold and SoulSilver. Strangely, the two Pokémon have completely different types. Fire and Psychic is a very unusual match up, this is also strange because Lugia knows Water-type attacks, giving Ho-Oh the disadvantage in battle. This may be a reason that these Pokémon have never battled each other in the anime. It is also known that if it flaps its wings, it causes a 40 days storm.
Lugia does not evolve, but in pokemon XD gale of darkness there is a shadow counterpart of lugia.
Lugia appears as a protagonist in The Power Of One. Lawrence III, a Pokémon collector, travels to the Shamouti Islands to add the Legendary Bird trio to his collection, and in the process hoping to lure out Lugia.
In the episode Around the Whirlpool when Ash and co. fall into a sea filled with Whirlpools, an unknown Lugia (the parent of the baby Lugia referenced below) saves them by calming the currents. They only see the silhouette of the Lugia for a brief moment though and are unable to properly identify the Pokémon.