"The official Super Smash Bros. website confirmed last week that Lucario shall be returning for the fight, for better or for worse.
Lucario first appeared in Super Smash Bros. Brawl and essentially replaced Mewtwo in terms of style and aesthetic. I was surprised to see that Lucario was confirmed this time around; I figured they would replace him with an equally stoic/quasi-psychic Pokémon from the latest generation. That being said, Lucario does play a small role in X and Y and is one of the lucky few who can mega evolve. I imagine Mega Lucario will be his final smash transformation.
While I have no strong feelings on Lucario’s confirmation, I’ve begun to have some qualms about how the Super Smash Bros. updates are being handled." - Stephen Hilger