I see a lot of people praising Mega Swampert for its insane bulk and Speed with SS, but I think it is being over-hyped quite significantly. I am not questioning the power of rain-boosted Waterfalls and STAB EQ's, but there are two major things that hurt Mega Swampart. First off, it has no reliable recovery. This hurts its bulk quite a bit since it will not be able to continuously come in on attacks and shrug them off, especially with all this priority flying around (no pun intended). However, what really puts a dent into M-Swampert is the fact it does not have access to the moves Swords Dance or Bulk Up (this thing looks like it took twelve cycles of steroids, yet Bulk Up wasn't a move Game Freak felt it deserved...). PuP isn't a bad move but only +1 Attack doesn't turn any 2HKO's into OHKO's that I know of. If Swampert could learn either move, it would easily be a top-tier threat that teams would have to prepare for. As things stand, Mega Swampert has the potential to be a decent sweeper, but will have to choose, after its STAB's, between Rain Dance, PuP, Superpower, Ice Punch, Low Kick, Stealth Rock, and possibly a couple special moves. Not only all this, but Mega Gyarados and Mega Sharpedo give Mega Swampert competition as a Mega rain sweeper. Gyarados didn't get trolled and received Crunch and Mega Sharpedo has stronger coverage moves and both of these mons have ways to increase their speed for the entirety of their time on the field.