Swampert

Swampert is one of DPP OU's most emblematic Pokemon. Its unique Water / Ground typing gives it many desirable traits. It resists popular Rock-, Fire-, and Steel-type moves, it's immune to sand and Electric-type moves, and it's resistant to Stealth Rock. In addition, it can hit a wide variety of foes thanks to its access to Ground- and Water-type STAB moves with Ice-type coverage. However, Swampert is 4x weak to Grass-type moves, which several Pokemon carry specifically to target it. Despite this, it makes for an awesome offensive pivot that is able to check many prominent threats like Jirachi, Heatran, Metagross, Tyranitar, and Zapdos.

However, Swampert does not have access to a reliable form of recovery, so it tends to struggle long term against strong attackers like Machamp and Infernape. Some Pokemon that Swampert checks decently, like Zapdos, Heatran, Jirachi, and Rotom-A, can also run status moves like Toxic and Will-O-Wisp, which considerably hamper its durability. Swampert's low Speed and harsh Grass weakness can also be exploited by Breloom if it does not have adequate support or enough Speed investment, the latter of which comes at the cost of its bulk.