It would be a mistake t' remove Lucario as it'd be both a disservice to Pokemon since he wholly deserves the character slot, and to his fanbase.
Interesting. Glad they came to their senses.
If it wasn't known before, there will be differing stages between the two versions. And I guess the 3DS will focus more on stages from handheld titles, and the Wii U will have console stuff. Didn't we see a Spirit Tracks and Awakening stage in the 3DS version? While the Wii U version had Skyloft? That actually makes a lot of sense, we should go back and look at that.Even though the characters will be the same in the Wii U and Nintendo 3DS versions, the arenas will be completely different. In the 3DS version, they are based on games released on portable consoles, while Wii U, arenas are based on areas from home console games.
Smash 4 will feature a Pokemon representative for the newer gens. Lucario is now outdated. I'd say the same would apply to other fighters such as Ike, possibly. I'm certain Mewtwo and Pichu have their own fanbases, but that certainly didn't mean anything when they kicked the bucket.
Or do you wish to supply some information I'm not aware of?
Pichu was removed for bein' a clone. Don't know why Mewtwo got the choppin' block, but so much as considerin' Mewtwo's return goes to show that Sakurai took note of the fans' outrage when Mewtwo was kicked out. If Sakurai respects Mewtwo's fanbase's cries, I can only imagine he wouldn't replace Lucario with the Gen 6 rep outta respect for Lucario's fanbase. That, and so he wouldn't commit the same mistake twice.
Furthermore, Lucario is still wholly valid in the realm of Pokemon. Despite bein' two and a half generations old (the half 'cause it was introduced prior to Generation 4), it's still constantly promoted by Game Freak in various roles 'n such. Go find my post detailin' all of that, as I can't be arsed to do it myself/Google all the information a second time.
Multiplayer makin' a game fun does not mean a game is good. PSAll Stars is shit.