^Eh?
Anyway, think about it.
There are 3 points brought up by Lucario supporters.
He was in a movie
He's fighting-type
He's popular
First, the movie. It's no secret that Lucario's biggest asset is that he was the star of a movie, making him a semi-major part of the anime. It's the whole reason you guys have a for the "Lucario For Brawl" thread versus the "Gengar for Brawl" thread.
Now, he is a prominent pokemon because of this, but lets take a look. Meowth was deconfirmed today, and who better represents the Anime besides Pikachu? His rival, Meowth. If Lucario deserves to be in, wouldn't Meowth deserve it more? He's in nearly every episode of the anime, and is a much more developed character. Yet he's only a Pokeball. If Meowth, one of the most prominent characters in the Anime, and probably the second most prominent Poke'mon, doesn't make it, what makes you think Lucario will?
Second, the type. Fighting type does not a shoo-in make. None of the previous Playable Pokemon have been fighting. He's got an interesting combination for sure, but does that have anything to do with Brawl? No.
Third, his popularity. I'll tackle the in-game usage popularity versus the real-life anime popularity (See "Movie" for why his Anime popularity is crap. There are many many pokemon more frequently used than Lucario, in game. Wobbuffet is a pokemon featured in almost all competitive teams, but I don't think he'll be getting in.
"But Lucario is the best possibility for all of these reasons!"
Ahem.
Meowth is more famous.
He's a good representative of your standard pokemon, as instead of a blue jackal, he is a normal-type cat.
He may not be popular (in-game), but that didn't stop Pichu or Jigglypuff, did it?
And yet he's denied. It's obiovus Meowth is a much better rep for the pokemon series than Lucario, but he's only a Ball pokemon. Don't get your hopes up.