Swampert

Swampert has reasonable 100 / 90 / 90 bulk which makes it an ideal defensive wall alongside its unique Water / Ground typing, which gives it one weakness, while sporting several resistances and one immunity. Swampert is one of the few Pokemon that stops Fire-type wallbreakers such as Darmanitan and Entei cold. Unfortunately, a 4x weakness to Grass-type moves makes it susceptible to easy OHKOs should one mispredict; however, Swampert's strengths far exceed any potential weaknesses. Access to Stealth Rock and Roar makes Swampert an ideal entry hazard shuffler. Furthermore, Swampert's Mega Evolution has access to Swift Swim and has base 110 / 110 defenses as well as base 150 Attack, making it an ideal rain sweeper. After using Rain Dance, Mega Swampert's Speed is doubled and alongside its huge base 150 Attack allows it to be an effective wallbreaker. However, the downside is that Mega Swampert suffers from a lack of any sort of reliable recovery, making it susceptible to being whittled down.