Aggron

Aggron solidifies itself as one of the best wallbreakers in PU thanks to its great offensive typing, decent Attack stat, and access to the coveted combination of Rock Head and Head Smash. Rock Head negating the recoil from Head Smash gives Aggron a spammable STAB move that, when coupled with Choice Band, can break through most physical walls in PU, such as Qwilfish and Regirock. Due to its weight, Aggron also boasts a high-Base Power Heavy Slam against most Pokemon, hitting Fighting-types like Gurdurr, which resist its primary STAB move. Aggron also has access to several coverage moves such as Aqua Tail, Earthquake, and Superpower that allow it to break through Pokemon that would normally wall it like Mudsdale and opposing Aggron. However, Aggron struggles against more offensive teams due to a middling Speed stat and an offensive typing that gives it 4x weaknesses to Ground- and Fighting-type attacks, both of which are common coverage options. Even though Aggron can use its Rock / Steel typing effectively offensively, it's a poor typing defensively; this, coupled with a low Special Defense stat, makes it difficult for Aggron to directly switch in or take attacks from faster foes, even against resisted special attacks. Along with being a wallbreaker, Aggron can also function as an offensive Stealth Rock setter, as it's one of the few setters with access to Taunt; however, even though Aggron is a decent offensive Stealth Rock setter, it faces stiff competition from Lycanroc and Golurk, both of which have other useful attributes, with Lycanroc being much faster and having priority and Golurk acting as a spinblocker and faring better versus Fighting-types.