Endangered Pokemon are exceedingly rare Pokemon that are hard to find in the wild. They take a lot of effort to find, and you may find yourself in a thread for pages before stumbling upon one.
Legendary Pokemon are the rarest encounters in Noctis. Only Admins may make Legendary Pokemon appear, and they may not be captured. Depending on the mood and personality of the Legendary in question, they may either aid you, offer you an item, or challenge you to battle.