Specially defensive Gastrodon stands out as one of the best special walls with a Special Defense donation thanks to its ability to deal with the most prominent special attackers in Tapu Koko. Scald discourages physical attackers like Rillaboom and Necrozma-DM from switching in by threatening them with a burn. Toxic cripples common defensive switch-ins, in particular Tangrowth and opposing Gastrodon. Clear Smog prevents bulky Pokemon with setup moves from muscling past it, especially Tapu Fini and Clefable, as they aren't afraid of Toxic. Earthquake can instead be used to better deal with Substitute users like Volcanion. Leftovers gives Gastrodon extra recovery and reduces the need to use Recover's PP. If opposing Spikes is a concern, then Heavy-Duty Boots is a viable alternative. Calm is the preferred nature on sets with Clear Smog, while Earthquake variant opts for Sassy to avoid reducing Earthquake's damage.

Specially defensive Gastrodon is seen on balance and stall teams as a reliable special wall. Gods with great Special Defense such as Ho-Oh and Giratina pair well with Gastrodon. Ho-Oh is a common partner thanks to their defensive synergy; Ho-Oh can take on Kyurem-W and Grass-types, particularly Kartana and Ferrothorn, for Gastrodon while Gastrodon deals with Water- and Electric-types like Volcanion and Tapu Koko. Other answers to Grass-types, notably Skarmory and Volcarona, also make great teammates. Strong physically offensive Pokemon such as Rayquaza and Victini can easily break through Gastrodon, which Rotom-W can handle. If Gastrodon forgoes Heavy-Duty Boots, the aforementioned Ho-Oh, Rotom-W, and Skarmory can also provide Defog support. Answers to Psychic-types like Mewtwo and Tapu Lele, which can target Gastrodon's weaker Defense stat with Psystrike and Psyshock, respectively, are necessary, so Steel-types like Necrozma-DM and Heatran or Psychic-types like Slowbro are recommended. On stall teams, Whirlwind from Giratina prevents Substitute foes such as Corviknight from using Gastrodon as setup bait. Cleric support from Clefable is also appreciated to help Gastrodon stay healthy.

Physically defensive Gastrodon can take on prominent physical threats such as Zeraora, Buzzwole, and Necrozma-DM while still being able to check several special attackers like Volcanion and Heavy-Duty Boots Tapu Koko. Scald discourages Steel-type Pokemon like Necrozma-DM, which don't fear Clear Smog, from trying to set up on Gastrodon and Grass-types like Rillaboom and Kartana from switching in thanks to its high burn chance. Clear Smog prevents non-Steel-types, notably Weavile and Buzzwole, from muscling through Gastrodon with their setup moves. Earthquake hits several Pokemon harder than Scald, among them Galarian Slowking and Heatran. Toxic is an alternative that cripples defensive Pokemon such as Tangrowth and Slowbro; however, frequent Scald burns make it not as effective, in addition to many of its checks having Regenerator remedying its usefulness. Rocky Helmet is preferred to punish contact moves, especially U-turn from the likes of Tapu Koko and Victini and Triple Axel from Weavile. Leftovers can be used instead to offset chip damage from entry hazards. Relaxed is the go-to nature to preserve Earthquake's damage, but Bold should be used instead if Toxic is chosen over Earthquake.

Physically defensive Gastrodon is typically found on bulky balance teams. Gods with high Defense stats, such as Calyrex-I, Groudon, and Necrozma-DM, are required to maximize Gastrodon's physical bulk. Grass-types, in particular Kartana and Rillaboom, easily OHKO Gastrodon, so teammates that can deal with them like Skarmory and Necrozma-DM make good partners. While Gastrodon can take on some special attackers, strong special wallbreakers like Kyurem-W still can break through it, so special walls such as Reuniclus make great partners. Reuniclus also enjoys Gastrodon's ability to deal with Volcanion and Tapu Koko which it can't properly check. Entry hazards hinder Gastrodon's role, which makes Defog support from Skarmory and Tornadus-T valuable.