Not really, as with the release of the Sixth Generation. Lucario get's a lot better Steel Type STAB move than Flash Cannon, though of course I'm not saying Flash Cannon is bad. It get's the new priority move, Bullet Punch. This is what made Lucario come back into the OU Metagame so fast. It lead with the priority Bullet Punch. Though Flash Cannon is still a good Special STAB move for Luc. Don't get me wrong there.