Gastrodon

One of the main allures of Gastrodon is its ability Storm Drain, which grants it an immunity to Water and acts as a critical Water-type move deterrent that benefits many of its potential teammates. This makes users of Muddy Water like Tapu Fini think twice before using the move, as they risk raising the Special Attack of Gastrodon while also negating non-spread Water-type attacks, such as those from Milotic and Araquanid.

Storm Drain often helps against rain teams, as it redirects Water-type moves from teammates so that they can threaten the sweeper. Due to the prevalence of Ludicolo on rain teams, Gastrodon is more of a check than a counter most of the time.

Gastrodon has a solid defensive typing that grants it resistances to a variety of types and an immunity to Electric-type moves, leaving only a 4x weakness to Grass. Gastrodon finds itself as a defensive glue on many teams due to the large number of Pokemon it checks, such as Incineroar, Landorus-T, Tapu Koko, Heatran, Nihilego, Zapdos, Mega Gengar, and Mega Manectric.

Despite having great Health and Special Defense stats, the poor Defense of Gastrodon limits its tanking potential. It can be heavily damaged by strong physical attackers such as Mega Kangaskhan, Mega Mawile, and Zen Headbutt Mega Metagross or OHKOed by some Z-Moves such as Tectonic Rage from Landorus-T or Excadrill.

Gastrodon has low Speed and rarely will outspeed anything even with Tailwind up, though this makes it all the more valuable against Trick Room teams.

Gastrodon faces competition when it comes to being a rain check from Ferrothorn, as Ferrothorn doesn’t have to worry about being OHKOed by Ludicolo and can threaten it or its teammates back with moves such as Power Whip. In addition Gastrodon faces competition from Tapu Fini for the bulky Water role on various teams, as Tapu Fini has access to many more moves such as Calm Mind and Heal Pulse and it has more bulk, Speed, and Special Attack.