>>18431782Because it isn't very good, isn't handed to you every time you play Black or White, and Gen V Dark was one of if not the worst type(s) in the game.
It doesn't help that Zoroark and Zorua were revealed at about the same time, while Lucario was assumed to be a legendary Pokemon until people could actually play through Diamond and Pearl; I remember that Serebii kicked off his leaks with a post saying that he wasn't going to speedrun the game or post things like "lel I'm battling Lucario XDDDD".
Oh, and Lucario's movie involved perennial fan-favorite Mew, while Zoroark shared the spotlight with Outclassed-by-Arcanine, Outclassed-by-Jolteon, and Suicune.
>>18431999Charizard, Mewtwo, Lucario, and Sylveon are the mascot Pokemon for Gen VI.
