Reminder that legendary Pokemon are not unique. They are simply rare and powerful Pokemon that legends formed around who won't or cannot breed in captivity. The only exceptions to this being explicit deity entities (i.e. Arceus) and man-made legends where explicitly only one exists (i.e. Mewtwo/Genesect). The movies are not and have never been canon to the games. Pokemon 2000 has been poisoning the brains of Pokemon fans for over two decades now on this.