That the reason why Mega Blastoise is weak compared to the others (assuming it remains the way it is, given it was revealed at the time of the other two and they were fully elaborated on at that time) is that it will get Shell Smash? If it got Shell Smash, you'd still be better off using your mega stone on another Pokemon who gets a bigger buff, and using regular Blastoise with Torrent (which would benefit it more than Mega Launcher even if it got a secondary pulse or if water pulse was buffed or even if it doubled water pulse's power) and a Focus Sash? I suppose it'd still fall to priority moves, but even without sash it'd have terrible defense after shell smash and it wouldn't be any different. --- Everything in life is a battle. Even peace itself is a battle to maintain it.