Legendary Pokémon
From Bulbapedia, the community-driven Pokémon encyclopedia.
Legendary Pokemon, in general, are Pokemon that have extremely powerful stats. In the games, you have one chance to catch them, and even then, catching them is a major challenge!
In the anime, Legendaries are considered "gods" in the Pokemon universe, appearing only to special trainers.
Some examples of Legendaries:
--Ho'oh (has appeared to Ash to guide him on his journey) --Mew (supposedly the descendant of all Pokemon, stars in the upcoming 8th movie) --Suicune (encountered by Ash at the beginning of the Johto arc; made a brief appearance in the 4th movie
