well i guess i should input my 2 cents, lucario is the only guy i use :D, this topic is an interesting one, but its going to end up with lucario as top dog (see what i did their?) because of his massive fanbase, and the thing is, everyone knows who mewtwo is, he is a dark insane pokemon that attempts to destroy all people and rule the world, been their done that, zoroak, while she is also mysterious she does not have such a huge fanbase, and she is a far cry away from his awsomeness, and most people already know her plot: save zorau at all costs, i heard that storyline before, meanwhile lucario however, is almost completly unknown, the only known one that had a true storyline died (well not technically), and his was done and dusted.
BUT as mentioned above, no one knows hardly anything about him and his species, and in SSBB he only had a scene or two before he was brushed off into the backround, but it leaves one to wonder, what was he doing floating on the icicle completly oblivious to the battle raging in the sky, why did he not feature a more prominant role? he certainly has the space, alot of unused character space there, and being completly ingnorant of a space battle a few metres above his head, proves he is calm and collected, he is a good guy, but the lone wolf (see what else i did there?) he seems like the silent type, only talking when he needs to, and being an assassin and soldier when the need demands it, but that could be changed. plus hes a badass, But his moves need to look more "powerful" as sunny said, and one last thing, what other pokemon has an inborn sense of justice and ability to bend aura with ease? plus being a martial arts master and looks like anubis, Lucario FTW