Aron

At a glance, Aron seems to be a generic Rock-type Pokemon, with a great Defense stat and a good Attack stat. However, a closer look at Aron reveals that it has access to the combo of STAB Head Smash and the Rock Head ability, allowing it to do enormous amounts of damage without taking recoil. It also sports an impressive nine resistances and one immunity, making it very easy to switch in and start wrecking havoc. Nonetheless, the tiny iron Pokemon is not without its flaws. The current metagame is crawling with Fighting-type Pokemon, all of which can quickly dispose of Aron. In addition to this, Aron's abysmal Speed stat means it will be easily revenge killed by faster Pokemon.