Mega-Mightyena
It took a while, I know. Sue me. We'll start simple, the artwork is done by mr-tiaa, whom you can find on DA and the sprite is made by Akuma-Tsubasa, whom you can also find on DA.
Type: Dark/Ghost
Ability: Strong Jaw
Stats:
HP - 70 -> 70
Attack - 90 -> 125
Defense - 70 -> 70
Sp. Attack - 60 -> 60
Sp. Defense - 60 -> 70
Speed - 70 -> 125
Strategies: Bring in Mightyena as a revenge killer, picking up a moxie boost in normal form before Mega Evolving into M-Mightyena, where strong jaw gives it an even greater boost in particular attacks. You know I'm a man of few words so I feel that there's little else to say.
As for the next poll - Your choices are as follows, Milotic, Claydol, Darmanitan, Quagsire, Luxray and Staraptor.