>>58700370The movie sold it to me as a character, not a species, similar to Mewtwo. Something that also helped was that its film had elements of the hero's journey, the master-student relationship between Sir Aaron and Lucario, which differed from the classic fighting dog of the Pokémon formula, as well as the heroic sacrifice, giving it a death on screen, unlike Latios's off-screen death.
Compare it to Zoroark, where it's just a wild animal looking for its cub, like in Jurassic Park. This worked against it; the audience didn't connect with it, giving Zorua more prominence as a character by giving it a voice and personality.
A middle ground was the Koko movie, where the monkeys are treated as a tribe, with individual characters like the old monkey, the antagonistic monkey, or Koko's father, but also showing the behaviors of the species. But this didn't matter because the story was a boring copy of Tarzan.