Magnezone

Magnezone has one job in the BW OU metagame, and it does that job well: trap and remove Steel-type Pokemon, particularly Skarmory, Ferrothorn, and Excadrill. Thanks to Magnezone's typing and ability, it can come in on most Steel-type Pokemon without much trouble and remove them. This makes Magnezone an enabler for Pokemon that are stopped by Steel-types, such as Latios, Garchomp, Landorus-T, Gliscor, and Amoonguss; making it the cornerstone of the famous DragMag style, where Magnezone clears the way for a collection of Dragon-type Pokemon to fire off powerful attacks. In addition, its ability to trap common entry hazard setters such as Ferrothorn and Skarmory and a common spinner and wallbreaker in Excadrill can make it a valuable teammate and take pressure off your spinner by reducing the need to spin as soon as possible. Also, thanks to its solid bulk, it can take weaker hits or resisted attacks from Pokemon such as Politoed and Latios in a pinch and get an attack off. However, Magnezone does not have much of an offensive presence beyond removing Steel-types due to its low Speed, and it has weaknesses to common attacking types, harming its overall viability.