On Wiki Spoiler I couldn't decide on the badass or the cute picture, lol. == General == *Unique Dragon/Dark typing is freaking badass, but leaves Hydreigon vulnerable to common Fighting- and Bug-type assaults. *Has NO solid counters. At all. *Great overall stats, with its obligatory 'pseudo legend' BST of 600 being fully abused. Hydreigon has power, bulk and decent Speed. Base 98 is awkward though, as fellow Dragons such as Salamence, Garchomp and the rare Flygon just slightly outpace it. *One of few pokemon who can easily beat the 'Jellithorn' (Jellicent + Ferrothorn) defensive core. *Ridiculous movepool, boasting attacking moves from EVERY type except Poison (which no one cares about unless it's STAB or Toxic (Spikes) anyway). *Near unrivalled wall breaking ability, due to its amazing movepool giving it access to powerful moves on both sides of the spectrum, with Fire Blast, Draco Meteor and Superpower being just some of them. *Levitate protects it from Ground moves and annoying Spikes/Toxic Spikes. *Faces some competition from the tier's many other Dragons for almost everything it does, but Hydreigon is able to find ways of sticking out. Having three heads tends to do that though, let's face it. == Mixdreigon == Hydreigon @ Life Orb / White Herb Ability: Levitate EVs: 4 Atk / 252 SAtk / 252 Spd Naive (+Spd, -SDef) or Hasty (+Spd, -Def) nature -Draco Meteor -Fire Blast / Flamethrower -Superpower -Roost / Dark Pulse / U-turn *What makes Hydreigon stick out more than anything else is its amazing wallbreaking ability. With some entry hazards in tow and careful prediction, the entire tier is 2HKOed at the worst by the right move. Isn't that something? *Even the mighty mixed wall Chansey is 2HKOed by Superpower after some prior damage (3 layers of Spikes would be ideal), meaning no pink blob will stand in Hydreigon's way of smashing through the opponent's team. *The Life Orb is by far the most recommended hold item here, as Hydreigon's wallbreaking power really needs that glowy pink orb to net many of its KOs. However, the White Herb has some use on this set by negating the stat losses from Superpower and Draco Meteor. While it doesn't help Superpower much (two Life Orb Superpowers will deal more damage in two turns), but with Draco Meteor it allows Hydreigon to fire off an absurdly powerful STAB attack twice. It's rare that this will be useful, as Hydreigon can simply switch afterwards, but it just may make a difference every once in a while. *Hydreigon uses a positive Speed nature so it can outrun as much as possible, but feel free to go positive Special Attack instead if you simply want more power. A Naive nature is the most recommended so that Hydreigon takes less damage from random Mach and Bullet Punches (with Conkeldurr and Scizor being notable users, respectively), while a Hasty nature prevents the rare Porygon2 or Z from getting a desirable Download boost, and helps Hydreigon sponge non STAB Ice Beams more easily. Choose whichever you feel will be more useful. *The EVs are simple, in spite of it being a mixed attacker. The Speed is maxed out to outrun as much as possible, and the Special Attack is also optimised for maximum killing power on the special side. The remaining 4 are placed into Attack to give Superpower a boost, although it'll rarely make a real difference. *Draco Meteor is the primary STAB in slot 1, mowing down just about everything that isn't a pink blob, Steel-type or defensive Jellicent, at the cost of halving Hydreigon's Special Attack after usage. *Fire Blast is recommended over Flamethrower in slot 2 for power, but if you need a move with accuracy you can rely on, Flamethrower's still perfectly viable, albeit noticeably less powerful. *Superpower in slot 3 is used mostly for Chansey (and elusive sister Blissey), 2HKOing the both of them with some passive damage, but it also scares a few other pokemon such as Heatran, Tyranitar and the rare Snorlax. *Finally, slot 4 is where Hydreigon is spoilt for choice. Roost is the most recommended option of the ones available, as it helps it stay alive for longer, allowing it to further abuse its respectable bulk and ambivalence towards entry hazards that aren't floating rocks. Dark Pulse is also perfectly usable, acting as a reliable STAB and giving Hydreigon a solid means of beating Jellicent, Reuniclus and other threats. U-turn is the last listed move because it acts as an emergency escape if you will, also dealing reasonable damage in the meantime. If you're lucky, it may even hurt a Celebi or something too. Earthquake is also viable in this last slot, being another reliable move with solid coverage that threatens Heatran a lot more, lets Hydreigon beat Jirachi in the rain (assuming no hax), and is just a good move in general. However, it's rarely seen because of its mostly redundant coverage alongside Superpower. *If you're not using Roost in slot 4, Wish support is HIGHLY recommended. == Subdreigon == Hydreigon @ Leftovers / Life Orb Ability: Levitate EVs: 252 SAtk / 4 SDef / 252 Spd Timid (+Spd, -Atk) or Modest (+SAtk, -Atk) nature -Substitute -Dragon Pulse -Focus Blast / Fire Blast -Fire Blast / Roost / Dark Pulse *Instead of simply destroying EVERYTHING, this Hydreigon paces itself a little more, and hides deviously behind a Substitute to ease prediction and protect it from deadly status. *The EVs and hold items are basically the same as the last set, although this one has the Leftovers available as the primary hold item for increasing Hydreigon's longevity. The Life Orb is still perfectly viable, but one must take into account the accumulated HP loss from both Substitute and Life Orb recoil before using the Life Orb. *A Timid nature is preferred to outrun as much as possible, but a Modest nature gives Hydreigon a bigger punch, and better complements its stat spread. *Dragon Pulse is chosen instead of Draco Meteor as the primary STAB this time, as Substitute Hydreigon prefers to stay in for more than one or two turns and thus doesn't want to use a self-crippling move like Draco Meteor. Dragon Pulse's base power isn't amazing, but it generally hits hard enough to accomplish whatever Hydreigon set out to do. *Focus Blast in slot 3 is the main coverage option. In spite of its poor accuracy, it's one of Hydreigon's best moves for this set, giving it perfect neutral coverage alongside Dragon Pulse (aside from the inviable Shedinja), threatens a lot of common Steel-type switch ins and even scares Tyranitar due to its 4x weakness to the move. However, if you don't like the idea of it missing at a crucial moment, Fire Blast can be used here instead, being a slightly more accurate move with the same base power and neutral coverage bar Heatran, and hitting a few Steel-types (such as Skarmory, Ferrothorn and Jirachi) a lot harder than Focus Blast. *Fire Blast is listed again in slot 4, obviously for the situations where both Fire Blast AND Focus Blast are needed on the same set. However, Roost is listed next to it, once again serving as reliable recovery. It's more or less mandatory if you're using the Life Orb as the hold item, but comes in useful in tandem with the Leftovers too. Finally, Dark Pulse gets another mention as the secondary STAB option, letting Hydreigon reliably beat Jellicent one on one, even if it has Taunt. Another option for this set would be Earth Power. If you're using Fire Blast instead of Focus Blast in slot 3, you'll need something that threatens Heatran and similar. Earth Power is practically the perfect solution, and it comes with the bonus of hitting Jirachi in the rain for good damage, too. == Choice Hydra == Hydreigon @ Choice Specs / Choice Scarf Ability: Levitate EVs: 252 HP / 4 SDef / 252 Spd Modest (+SAtk, -Atk) or Timid (+Spd, -Atk) nature -Draco Meteor -Fire Blast / Flamethrower -Focus Blast / Earth Power / Surf -U-turn / Dark Pulse *While rarely seen nowadays, Hydreigon is still an extremely potent choice item abuser, using its typing and movepool as a means of separating itself from the myriad of other Choice dragons in OU. *Once again, the EVs remain more or less unchanged, while a Modest nature is recommended with the Choice Specs, and a Timid with the Choice Scarf. *Draco Meteor is the primary STAB again, flattening basically the entire tier except for Chansey and some Steel-types with the Choice Specs. As most choice sets function as hit and run attackers, Draco Meteor fits it more or less perfectly. *Fire Blast and Flamethrower are prime coverage options, boasting all but perfect neutral coverage alongside Draco Meteor, and both are useful for hitting the ever so common Steel-type switch ins. All but Heatran will feel the wrath of burning flames, should they switch in at the wrong time. Fire Blast is for power, while Flamethrower is much more reliable, but less recommended with the Choice Specs as that set generally wants to hit as hard as possible. *Focus Blast on slot 3 is again almost needed, perhaps on this set even more than the previous. With some luck, a Choice Specs Focus Blast will 2HKO Blissey, as well as annihilating basically any Heatran and more or less everything else that gets in its way. However, there are times when Focus Blast isn't called for, or you can't rely on its accuracy. Earth Power gets a mention next to Focus Blast as it hits Heatran even harder than Focus Blast (unless it has an Air Balloon), and also beats Jirachi in the rain. It comes with the cost of dealing far less damage to Tyranitar and failing to even scratch Blissey, but if Tyranitar and Blissey are otherwise taken care of (perhaps with a bulky Fighting-type like Conkeldurr?), Earth Power becomes a very attractive option. Lastly, Surf gets a mention because, not only is it an unexpected move to see on Hydreigon, but it also hits Heatran reliably, and can be used for pseudo STAB in the rain, letting Hydreigon muscle its way past Steel-types that aren't named Ferrothorn without even using a Fire move. Situational, but deadly in those situations. *In slot 4, U-turn gets the main listing for scouting purposes, letting Hydreigon see what it's up against and also dealing reasonable damage as well. If U-turn doesn't appeal, Dark Pulse gets a mention yet again as a secondary STAB that can easily beat Jellicent. It also serves as the reliable STAB option on this set if you choose is, as Draco Meteor is the primary STAB again. If you're using U-turn, consider a neutral Attack nature such as Rash or Hasty. If neither U-turn nor Dark Pulse works for you, give one of slot 3's unused options a try, or even consider Dragon Pulse for a backup STAB. == Other Options == *As previously mentioned, Hydreigon has an incredible special movepool, letting it attack with a move of almost every type in the game. It therefore stands to reason that some of this movepool should be mentioned. *While Hydreigon's Attack stat is inferior to its Special Attack by quite a margin, a base 105 is by no means bad, and Hydreigon's movepool includes Crunch, Outrage, Acrobatics, Head Smash and Aqua Tail among many, many others. Feel free to give a physically based or even Choice Band set a try if you want, although don't expect it to be amazing. Tri Attack and Charge Beam are sadly the only notable special options, but neither of them have any particular reason for usage. *Thunder Wave exists in Hydreigon's movepool, but most of its common switch ins won't be fazed too much by the move, and its Speed isn't low enough to require Thunder Wave support (in most cases). A weird defensive set can be tried, as Hydreigon has the combination of Roost, Taunt, Thunder Wave and Dragon Tail at its disposal. However, aside from Taunt, there's basically nothing this set has over Dragonite. Toxic's already there, but there are very few cases where Hydreigon would need to poison something in order to bring it down. *The Lum Berry is an alternate option for a hold item, as it means that Hydreigon can worry less about status. Weakness reducing berries such as Haban and Yache are also worth considering. *Work Up is a boosting move, but Hydreigon really does not have the room for it. Rain Dance and Sunny Day can be used as backup weather once the weather war has been won, and Hydreigon can easily find time (but not necessarily room) for the moves. == Checks and Counters == *By definition, a counter is something that can switch into every set without fear, and beat the pokemon it switches into before the pokemon in question can KO it. Following this logic, it quickly becomes clear that Hydreigon has NO counters. There is literally nothing in the tier that the right set can't threaten. *Of all the pokemon in OU, Chansey comes closest, only losing out to two Superpowers from the mixed set if the pink blob has taken enough prior damage (around 35% is usually necessary). If Chansey survives the two Superpowers, it can simply heal off the damage and either stall Hydreigon out with Toxic, a recovery move and Seismic Toss, or cripple it with Thunder Wave and let something else handle it. *Heatran doesn't fear Hydreigon's common Dragon + Fire type coverage, and can bring it down with its own non STAB Dragon Pulse, however Focus Blast or Superpower will rustle its jimmies, as will the rare Earthquake, Earth Power or even Surf. Tyranitar is in a similar boat, fearing only Superpower and Focus Blast, and otherwise being able to maul Hydreigon with a Superpower of its own, or perhaps a couple of Stone Edges. *Jirachi in the rain can take just about anything (Specs Earth Power will hurt a lot), and can hax Hydreigon to death with the combination of Body Slam paralysis and Iron Head flinching. Other Steel-types aren't so lucky in terms of surviving, but most of them can tank a Draco Meteor and use the halved Special Attack to their advantage. If Hydreigon is choice locked, even better for them. While unorthodox, Jellicent gives Hydreigon trouble if it lacks Dark Pulse or Draco Meteor, due to being able to sponge just about every other move reasonably well, having reliable recovery and the ability to whittle Hydreigon's HP away from it with Toxic and Ice Beam. *Powerful priority moves such as Breloom's Mach Punch and Mamoswine's Ice Shard are decent means of revenge killing Hydreigon, seeing as its own Life Orb generally leaves it in the KO range for both moves. Scizor's Bullet Punch is another worthy option, but Hydreigon can survive it most of the time. Choice Scarf Dragons such as Salamence, Kyurem-B and the Lati twins can all revenge kill Hydreigon fairly easily, as they are all naturally faster (except for Kyurem-B, assuming both are running the same nature) and can pummel Hydreigon with their own Dragon STAB. Dragonite's Multiscale lets it survive almost any hit from Hydreigon (basically anything but a Choice Specs Draco Meteor) and strike back with its own Dragon STAB, but this should really be a last resort, as it's a fairly situational answer.