Hydreigon's solid defensive profile and decent Speed tier make it an effective wallbreaker with Nasty Plot, giving it ample opportunities to set up against the likes of Aegislash, Slowbro, and Rotom-Wash. Dark Pulse, when boosted by Darkinium Z, allows Hydreigon to overwhelm many specially defensive Pokemon after a boost, such as defensive Celesteela barring Protect. Flash Cannon allows Hydreigon to hit Clefable and Enamorus super effectively, potentially OHKOing non-Unaware variants of the former after a boost while potentially OHKOing the latter after Stealth Rock. Alternatively, Earth Power in conjunction with Groundium Z allows Hydreigon to put more immediate pressure onto the likes of Clefable, Tyranitar, and Tapu Fini at +2; it also scores an immediate OHKO on Iron Moth without the need to burn its Z-Crystal. Roost allows Hydreigon to offset status damage from Hippowdon and Gastrodon, keeping it healthy enough throughout the game to repeatedly bombard the opposition. However, Substitute in conjunction with Leftovers allows Hydreigon to set up safely on the likes of defensive Pokemon that can't touch it, such as Hippowdon, Slowking, and Skeledirge. Hydreigon fits best on bulkier teams that appreciate its unique mix of defensive utility and offensive firepower. Defensive staples such as Clefable and Aegislash are all sufficient at pivoting into Fairy- and Fighting-types that Hydreigon may have a hard time playing around, such as Enamorus, Mienshao, and Buzzwole. Clefable also has access to utility moves such as Knock Off that can help wear down some of Hydreigon's checks long-term, like defensive Celesteela and Chansey. Hydreigon is easily revenge killed by faster threats such as Alakazam and Keldeo, making additional defensive partners that can respond to these Pokemon, such as Gastrodon, Assault Vest Tangrowth, and Slowking extremely valuable, letting Hydreigon maximize its wallbreaking efforts despite the presence of these Pokemon. Additionally, pivoting support from the likes of Iron Moth, Scizor, and the aforementioned Slowking can aid Hydreigon in finding safe entry against many of its defensive targets, preventing it from being worn down or threatened by potential coverage options and status that would otherwise be aimed at it, such as Close Combat from Aegislash or Thunder Wave from Rotom-Wash.

Choice Specs Hydreigon is a potent wallbreaker, being able to threaten common special walls such as Celesteela with its powerful STAB moves and coverage options. It also has more longevity and defensive utility, including a resistance to Pursuit, at the cost of Speed and more consistent STAB moves compared to other special wallbreakers like Iron Moth. Draco Meteor OHKOes threats like Iron Moth and Mega Heracross while doing significant damage to foes such as Galarian Moltres and Mega Sableye. Dark Pulse threatens Slowking and gives Hydreigon a spammable STAB move. Flash Cannon hits Fairy-types like Enamorus, Mega Gardevoir, and Clefable. Fire Blast threatens Celesteela, Tangrowth, and Bisharp, Roost takes advantage of forced switches and lets Hydreigon stay healthy to switch in several times throughout the match, while U-turn lets it pivot out of foes it can struggle against such as Azumarill and Clefable. A Timid nature lets Hydreigon outspeed Excadrill, while Modest gives Hydreigon even more power. Hydreigon struggles to break through Fairy-types such as Azumarill and Clefable, as well as Celesteela if not running Fire Blast, so teammates that can pressure them like Thundurus and Mega Venusaur are helpful. Hydreigon also appreciates pivots such as Victini and Slowking that can safely get it onto the field; Victini can use U-turn to pivot out of switch-ins that Hydreigon threatens like Slowbro and Mega Venusaur, while Slowking can safely pivot it in with Teleport. Knock Off support from the likes of Mega Vensaur, Clefable, and Thundurus is appreciated to help Hydreigon break through Pokemon like Celesteela and Assault Vest Tangrowth. Setup sweepers like Booster Energy Iron Moth and Galarian Moltres benefit from Hydreigon's longevity and ability to pressure their checks such as Mega Venusaur and Tyranitar, respectively, allowing them to become wincons late-game; fast teammates such as Choice Scarf Enamorus and Keldeo also appreciate Hydreigon for this reason, with it being able to pressure their switch-ins such as Slowking and Assault Vest Tangrowth, which can open the way for them to clean late-game. Hydreigon can also easily be revenge killed by faster Pokemon such as Hawlucha, Alakazam, and Enamorus; Skarmory can deal with Hawlucha while providing Spikes support, and Celesteela can deal with Alakazam and Enamorus.