Hydreigon is a frighteningly powerful special attacker with spammable STAB moves in the form of Dark Pulse and Draco Meteor and a myriad of crucial coverage options such as Fire Blast and Flash Cannon. It also possesses a great typing, solid bulk, and an immunity to Ground granted by Levitate. These perks allow it to come in on a swath of attacks such as Earthquake, Thunderbolt, and Psyshock. While its Speed tier isn't anything fantastic, it's just enough to outpace threats such as Tapu Lele, Zygarde, and Landorus-T. However, Hydreigon faces fierce competition from Hoopa-U and Ash-Greninja as a Dark-type wallbreaker, as well as from Choice Specs Latios as a Dragon-type wallbreaker. It also struggles with the presence of many influential Fairy- and Fighting-types in the tier such as Tapu Fini, Tapu Koko, Mega Mawile, Keldeo, and Terrakion.
name: Choice Specs
move 1: Draco Meteor
move 2: Dark Pulse
move 3: Flash Cannon / U-turn
move 4: Fire Blast
item: Choice Specs
evs: 252 SpA / 4 SpD / 252 Spe
Draco Meteor is a devastatingly powerful STAB attack that mauls anything that doesn't resist it while also doing solid damage against Pokemon that do resist it. Dark Pulse is Hydreigon's safest STAB option with nearly no drawbacks and breaks past many bulky Pokemon such as Mega Scizor, Toxapex, and Mega Sableye. Flash Cannon hits Fairy-types such as Clefable, Mimikyu, and Tapu Bulu. U-turn can be used to pivot out of unfavorable situations. Such instances include predicting an incoming Fairy-type switch-in or an especially bulky wall such as Chansey. Fire Blast razes Steel-types such as Magearna and Mega Mawile.
A Timid nature is used to outspeed slightly slower Pokemon such as, Tapu Lele, Zygarde, Landorus-T, and Kyurem-B. Modest is an option to pick up notable 2HKOs such as on Toxapex and Mega Scizor with Dark Pulse, but the Speed loss is monumental. Maximum Special Attack investment along with Choice Specs allows Hydreigon to hit as hard as possible.
Hydreigon is best used as an early-game wallbreaker, weakening walls for another teammate to come in later and sweep. Dark Pulse should be used most often,as few noteworthy targets resist it and it bears a nifty 20% flinch chance. Draco Meteor is a very powerful move, but it invites in Fairy-types, causing you to concede momentum. It also bears a nasty Special Attack drop that can give the opposition the upper hand, whether it be by allowing them to set up with a sweeper or set up hazards. Coverage moves should only be used if you're predicting a threat such as Magearna or Clefable to switch in. Be sure you predict well,as Hydreigon depends on its coverage moves to muscle past Fairy-types. Don't hesitate if you have to switch Hydreigon into a resisted attack, as its bulk is usually sufficient to take one.
Pokemon that can trap and weaken or outright beat Chansey such as Dugtrio and Magma Storm Heatran are greatly appreciated. Pokemon that appreciate Hydreigon's wallbreaking prowess so they clean up like Shift Gear Magearna, Rock Polish Landorus-T, and Swords Dance Mega Mawile make great teammates. Teammates that can take on opposing Fairy-types such as Tapu Fini, Clefable, Tapu Lele, and Tapu Koko are a necessity. Steel-types such as, (RC) Magearna, Mega Mawile, Jirachi, Ferrothorn, and Heatran are great choices for this role. It's worth noting all of these Steel-types with the exception of Magearna are also able to set Stealth Rock to assist Hydreigon in achieving KOs. Hydreigon also appreciates teammates that can beat fast Fighting-types such as Keldeo and Terrakion. These teammates include Latios, Latias, and Mega Alakazam. Amoonguss and Assault Vest Tangrowth are also great teammates for dealing with Keldeo, but not Terrakion; however, physically defensive Tangrowth can stomach hits from Terrakion.
Life Orb allows Hydreigon to switch moves, but the recoil and noticeable drop in power is unappealing. Choice Scarf is an option to pressure offensive teams more, as well as offer a surprise factor, but Hydreigon is more at home ravaging bulkier teams with Choice Specs. A set utilizing Taunt and Roost can be used to apply more consistent pressure against stall and balance builds due to the freedom of switching moves combined with Taunt and recovery.
Checks and Counters
**Fairy-types**: Hydreigon's greatest bane is its susceptibility to Fairy-types such as Clefable, Tapu Fini, Azumarill, Mega Mawile, and Magearna. These Pokemon are usually able to come in on both its STAB moves and retaliate with their own super effective STAB attacks.
**Fighting-types**: Although most cannot switch in safely, Fighting-types such as Terrakion, Keldeo, and Mega Medicham all outspeed Hydreigon and can strike it down with their Fighting-type STAB moves. It's worth noting that most barring Mega Medicham are able to come in on Dark Pulse.
**Dragon-types**: Hydreigon is on the slow side as a Dragon-type, so it's rather susceptible to being KOed by faster Dragon-types such as Latios, Garchomp, and Mega Charizard X.
**Specially Defensive Pokemon**: Due to their immense special bulk, Hydreigon cannot easily break through Chansey, Mandibuzz, and Assault Vest Tornadus-T. While the latter two are at a higher risk of being KOed due to their Stealth Rock weakness, Chansey takes negligible damage and can wear it down through Seismic Toss and Toxic or cripple it with Thunder Wave.
**Faster Pokemon**: Faster Pokemon such as Keldeo, Terrakion, Garchomp, and Greninja can threaten to KO Hydreigon with their powerful STAB moves.