Gastrodon

Gastrodon has a solid niche as a special wall due to it possessing a great defensive typing in Water / Ground combined with a high HP stat and decent Special Defense. Gastrodon stomachs numerous hits comfortably from menacing special wallbreakers such as Gengar, Nidoking, and Choice Scarf Hydreigon, and its Ground typing blocks Mega Manectric’s and Rotom-H’s Volt Switch and shuts down vital momentum. Storm Drain also grants a Water immunity for Gastrodon that makes it a solid switch-in to Tentacruel, Mega Blastoise, and Volcanion. What really sells Gastrodon compared to its Water / Ground counterparts in Swampert and Seismitoad is its access to reliable recovery, which further bolsters its strong defensive typing and lets it continuously check the aforementioned threats. However, Gastrodon lacks the ubiquitous Stealth Rock, unlike Swampert and Seismitoad, in a metagame that's favorable towards role compression. Gastrodon's typing is only weak to Grass, but it openly invites Grass-types like Celebi and Amoonguss onto the field with no repercussions and gives them free turns to act. Gastrodon is also a passive Pokemon that leaves it set up on by common sweepers such as Mega Altaria and Togekiss.