Mawile

In previous generations, Mawile was always a disappointing package of a Pokemon, with cool abilities and an interesting movepool but without the tools needed to use them due to its horrid base stat total. Gen 6 was awfully kind to Mawile however, giving it a very useful secondary typing in Fairy and a Mega Evolution that boosts its Attack to obscene levels with not only a stat boost but the coveted Huge Power. Life isn't perfect for Mawile, as its two weaknesses are both extremely common, it's painfully slow, and it's plagued by the common Intimidate and Will-O-Wisp, but it's more than powerful enough to pull its weight. Mawile is now a Pokemon whose useful defensive typing, possession of Intimidate before Mega Evolution, and Attack stat that makes Kyurem-B blush post-Mega Evolution has it sitting pretty as one of the ruleset's best Pokemon.