First of all I'm going to say I am one of those people that hate the idea of lucario being in brawl. I just want to make that clear.
I don't think Lucario is going to make it at all. From my experience, every pokemon thats been in the ssb series have been pokemon that appear in red/blue (except pichu, I will talk about him in a second). There is pikachu, jigglypuff, mewtwo, and now the pokemon trainer with squirtle, ivysaur, and charizard (all red/blue pokemon). Sure, there is pichu in ssbm, but he's a clone, and I'm highly sure pichu won't make it, mainly since one of pikachu's costumes is the blue goggles on his head (one of pichu's costumes). Another reason why I think pichu won't be making it is because he is a clone that not only has the same attacks as pickachu, but also is the same, electrice type pokemon, as pikachu. Therefore that excludes pichu.
(Yes I have realised I drifted off topic with lucario)
With lucario, it's the same scenario about him not being a red/blue pokemon. He's a new one made for the ds. I personally don't see why he's so popular, compared to any other pokemon. He's a fighting type (I believe; I haven't played the ds game nor do I plan to) that would make a good addition, but there are other characters in brawl that could easily be a fighter. If anything, since he's so popular, he should be a pokeball. I personally hate the idea of adding such a new pokemon onto ssbb as a playable character. Not to mention what his alternate colours would be, lol

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Anyways that's my explanation why I believe pichu, nor lucario, will make it.
(Btw I am aware that it's going to be a "Me against everyone else that posts" sort of argument here, so I'm ready. Reinforcements would be nice :])