The Legendary Pokémon, also called "God Pokémon," are Pokémon of immense might and that are seen in various legends, mythologies, and rumors worldwide. While some Legendary Pokémon seem to be unique to themselves, others are part of a rare but powerful species.
During Lualdi's Colonial Era, the settlers did battle with the Legendary Pokémon and eventually subdued them. Records indicate that some of the kingdoms of that area had alliances of some kind with the Legendary Pokémon, though there is no proof that these weren't just colonist hyperbole or mistaken accounts.
Seeing a Legendary Pokémon is a rare event, but there is evidence that despite their defeat long ago, some of them still remain in Lualdi -- just out of sight and away from human eyes, for the most part. They do not let themselves be captured easily, if at all. In fact, conventional Lualdian Poké Balls do not appear to work on Legendary Pokémon. Receiving a Legendary Pokémon's assistance would theoretically require convincing one to help, and even then, they would likely come and go as they please.