Registeel

Registeel serves the purpose of a bulky ChestoRest + Double Dance sweeper, as its bulk, combined with its amazing Steel typing, gives it the edge in a multitude of matchups. It is able to set up on common UU staples such as Nihilego, Chansey, and Scizor and bait offensive threats that hit it super effectively, such as Zygarde-10%, Conkeldurr, and pivot Thundurus-T, using them as setup fodder to start a sweep. Because of its ability to boost its physical and special bulk, Registeel has multiple opportunities to set up and can potentially steamroll teams lacking a Ghost-type, Taunt, or certain sweepers that don't take much from Body Press. It also has a good amount of PP on Iron Defense, Amnesia, and Rest combined, so it is able to stall out defensive Pokemon like Slowking and Amoonguss. Registeel is also a solid defensive Stealth Rock setter for many teams, checking various offensive threats, including Nihilego, Zarude, and Starmie. It also has access to status in Thunder Wave and Toxic, which makes it less passive against offensive teams. However, while Registeel's defensive profile is phenomenal, its passivity leads to inviting common wallbreakers and setup sweepers in, like Keldeo and Nidoking. It also faces stiff competition as a Steel-type Stealth Rock setter from the likes of Excadrill and Cobalion, both of which have an actual offensive presence. Registeel faces competition as a defensive Steel-type from Skarmory and Scizor; both have reliable recovery and Skarmory can check Pokemon like Gyarados and Diggersby. Registeel also greatly fears Knock Off because of how reliant it is on its item to stay healthy throughout a game. It's also often forced to use Rest between boosting, which gives wallbreakers like Keldeo and Nidoking chances to fish for critical hits to KO it through its boosts.