Hydreigon; the first ever hybrid Dark-Dragon Pokemon ever. My top two favorite types finally combined onto a single Pokemon, yay! 6 resistances, 3 weaknesses (all of which very common attacks), 2 immunities (one from it's Ability), and very good offensive coverage (only Steel resists both types) it's a very good Pokemon. 98 base Speed is...odd, but not horrible. Although good in OU, I personally found Hydreigon to be laughable prior to the Move Tutors of Black2/White2. I mean, seriously, it can't learn Dark Pulse unless you trade over a Gyarados that was taught it back in Generation IV? (That's what my research showed: Gyarados shares an Egg category with Hydreigon, can be taught Dark Pulse via TM, it's an Egg move for Hydreigon...you get the rest.) Anyways, here are my set ideas.
Back in my day, we used swords not fancy guns!
~Dragon Pulse
~Flamethrower/Fire Blast
~Surf
~Hyper Voice/Tri Attack/Flash Cannon
Item Attached: Choice Scarf/Life Orb
Ability: Levitate
EVs and Natures: 252 Special Attack/252 Speed/4 HP
Timid (+ Speed, - Attack)/Modest (+ Special Attack, - Attack)
Pre-Black2/White2 Moveset. Dragon Pulse is your standard go-to attack. STAB, hits most things for neutral, good PP, this ought to be on every Hydreigon. Flamethrower has that perfect coverage as described in Reshiram's file; Fire Blast is for those who prefer the trade off of higher accuracy and PP for power. Which is...99% of the people who are members of this site/who write up the POTW. Surf has good coverage, good power, and is your best weapon against Terrakion (there's also Earthquake, but 105 Attack compared to 125 Special Attack?). It also hits most Steels neutral and is the only Special Attack it has (again, pre-Black2/White2) that'll hurt Heatran. The last move is just for filler. Hyper Voice has good power and invokes Skyrim memes (I even named mine in White Alduin), plus most Pokemon who can safely switch into it have little to no business switching in due to Hydreigon's other possible moves. Tri Attack is weaker, but has the possibility of inflicting a Status onto your opponent. Yes it's random, low chance of happening, and may bring about your own defeat (ex. giving a Burn to something with Guts), but the possibility of ruining Magic Bounce users with a Status they'd usually laugh off (such as Espeon with Paralysis) is enough to warrant at the least a "gimmick" mention. Plus it's one of a handful of Dragons who can inflict Freeze Status semi-reliably. (Kyurem is the other; most others don't have the moveslots for Ice Beam or in Dragonite's case Ice Punch. Plus Dragon as an offensive type tends to hit most things Ice would and more anyways so how often does one see a Dragon and an Ice move on the same Pokemon?) Flash Cannon also hits Terrakion and Tyranitar like Surf, but with the chance of a Special Defense drop. Have I mentioned that before, that Flash Cannon does that Special Defense drop bit? Other than that, your other moves tend to leave Flash Cannon on the sidelines, so save this for Double Battles when you have a Serene Grace-equipped partner.
Items are fairly self-explanitory. Choice Scarf makes up for Hydreigon's Speed (oh the things that outrun this Dragon!) and is preferred over Choice Specs since you've got a strong 125 base Special Attack to work with already. (Though the extra power is always nice...) Life Orb boosts the power of Hydreigon's attacks while cutting your own health. Just make sure you run an EOD unit on your team (Espeon, Rapid Spinners, etc) so you don't KO yourself sooner. (EOD, for those not familiar with the term, means Explosive Ordinance Disposal; a sub-branch of the US Navy that gets rid of land mines, IEDs, and other hazards. A fitting term for Pokemon who exist competitively just to get rid of field hazards, no?)
Welcome to the future!
~Dragon Pulse
~Flamethrower/Fire Blast
~Earth Power
~Dark Pulse
Item Attached: same as above
Ability: Levitate (it's the only Ability it gets.)
EVs and Nature: same as above
Post-Black2/White2 moveset. It works the same as the previous set, but with two different, key attacks. (Side note, for those who "breed perfection" this set can be created legally by breeding a Hydreigon with a Gyarados who was taught Dark Pulse in Gen IV and whatever's breedable with Hydreigon that knows Earth Power. I don't.) Earth Power is slightly weaker than Surf and hits most of what the Water move also hits. The differences are fairly huge, however: a chance to lower the foe's Special Defense and a X4 hit on Heatran (who, as stated for Reshiram, is the only thing that resists the Dragon/Fire offensive combo). Dark Pulse is your other STAB move, and a good one too. Hits Psychic and Ghost types hard, and the Flinch chance always helps even if your opponent has a counter in.
† I am a Christian and proud of it! Copy and paste this if you are too.†
-Take up thy cross and follow Christ Jesus.
~Don't underestimate my God~
♥I believe in Jesus Christ as my Savior. If you do too and aren't scared to admit it, then copy and paste this in your signature.♥
I don't calculate stat values, I don't use cheating devices, I don't breed my way to perfection, and I don't care about natures. I catch my Pokemon the way they are, and treat them like individuals instead of brainless drones. If you use this philosophy, copy & paste this into your signature. (Started by Tyranitar, "I don't use "uber" Pokemon," edited out by me because I do use "uber" Pokemon on occasion.)
for Hydreigon
LeafGreen 
HeartGold 
White 2 
Originally Posted by Blue Harvest
(Jeremiah) Level 5
(Cinder) Level 16 - Fury Swipes, Yawn, Lick, Incinerate
(King) Level 18 - Tackle, Focus Energy, Razor Shell, Water Sport
(HM Slave) Level 10 - Leer, Cut, Bite, Bide
(Sasha) Level 7 - Leer, Tackle, Oder Sleuth
