Diddy confirmed = highly requested character confirmed = Lucario confirmed
Diddy confirmed = character without any fancy schmancy transformation skills or stuff but with a unique style confirmed = Lucario confirmed
-> Farfetched assumptions confirmed
Still, if Sakurai could make Diddy unique and opted against the Diddy-Dixie team, I see that as a good sign for the supposedly not unique Lucario.
Lucario didn't appear anywhere on the Sakurai poll. o_O I mean, as popular as he is, I really only see him being requested in North America, unless there's a Japanese board with a big fanbase that I'm not aware of...
Brings some minor hype to Gardevoir, though....I mean correct me if I'm wrong, but when the poll was taken, wasn't Diamond/Pearl already released in Japan? And Lucario was revealed to Japan way before then, yet of all Pokemon, only Gardevoir made it and it was mentioned once. Very worrying.
One more point against our poor friend Lucario is that Sakurai seemed to have put in a second gen character as a last thought for Melee. You get the returning Pikachu and Jigglypuff, newcomer Mewtwo and when the time boils down "Man, we need to make clones! Uh, Pichu!" If it was so important to rep the second gen at the time, why didn't we get an original second gen character alongside Mewtwo?
I still wish Lucario fans the best of luck, but if he ends up replacing Jigglypuff or Mewtwo I will be very disappointed. You don't replace a 2 game veteran and the most voted Pokemon/villain representative. That's just not cool. =/