Aggron

Aggron is one of the strongest wallbreakers in the RU tier. With a great Attack stat, Rock Head, and access to STAB Head Smash, it can be one of the single hardest Pokemon to switch into. This is amplified by the fact that Aggron has options for most of the Pokemon in the tier that can handle its powerful Head Smash. Secondary options, such as Heavy Slam, Low Kick, and Fire Punch, allow Aggron to push through potent Rock-resistant Pokemon, like Flygon, Rhyperior, and Bronzong, with the greatest of ease. Aggron's typing also provides it with key 4x resistances to Normal- and Flying-type moves to grant it some opportunities to switch in. However, with that typing comes some severe drawbacks. 4x weaknesses to Fighting- and Ground-type moves combined with a subpar base 50 Speed stat mean Aggron will almost always be forced out after it gets a KO. While it has a fantastic Defense stat, its somewhat low HP and lackluster Special Defense are certainly not doing it any favors, which lets many significant special attackers force it out. While its Head Smash is incredibly powerful and it does have coverage for many of the Rock-resistant Pokemon in RU, the likes of Seismitoad and Poliwrath can stand up to it most of the time.