Claydol

Claydol plays a fundamental role in ADV OU as one of the best spinners in the metagame. Spinning away Spikes is a great source of support for its teammates, and having a spinner that is immune to Spikes like Claydol is a godsend for many teams. Furthermore, Claydol's immunity to sand and good defensive typing raise its profile as a spinner, despite Starmie's higher Speed and ability to pressure Skarmory. Claydol also packs a Rock resistance and a Ground immunity that allow it to pivot into common attacks like Rock Slide and Earthquake from the likes of Tyranitar and Aerodactyl, and its Electric immunity is handy for pivoting into Thunderbolt from Zapdos and Jolteon.

However, Claydol's lack of a recovery move means it cannot take repeated hits from attacks like Tyranitar's Hidden Power Bug, Zapdos's Hidden Power Grass, and Aerodactyl's Double-Edge. Additionally, despite Claydol's good defensive typing, it cannot threaten back a lot of the Pokemon that it's supposed to check without committing to Explosion. Furthermore, it tends to lose momentum when it goes for a Rapid Spin, as six glaring weaknesses to common attacking types like Water, Ice, Grass, and Bug mean it can be taken advantage by threats such as Heracross and offensive Water-types, and it's often forced to blow up to prevent setup from threats like Calm Mind Celebi and Calm Mind Suicune. Additionally, Claydol can't make progress by switching directly into the opposing Spiker if it's Cloyster, Hidden Power Bug Forretress, or Drill Peck Skarmory, as it will be forced out, leaving at least one layer of Spikes on the field; however, against Toxic + Protect Skarmory it can stay in safely as long as it has Refresh.