This is in regards to the new generation 8, for Battle Stadium and SS OU.
The new meta is very kind to Hydreigon, with its previously lacking speed is now actually pretty decent. The decreased power level making Hydreigon's above average bulk even better.
The biggest change though comes in the form of movepool expansion. Hydreigon has gotten 3 significant moves this generation: Nasty Plot, Dragon Dance and Hydro Pump.
Hydreigon @ Life Orb
Ability: Levitate
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Nasty Plot
- Dark Pulse
- Draco Meteor
- Flash Cannon/ Focus Blast/ Fire Blast/ Belch
The standard Hydreigon set, very effective at wallbreaking. Pretty prediction-reliant though, you'll have to think what your opponent will do and play accordingly. Don't be in a hurry to set up, sometimes it's better to just attack if you predict a switch. Nasty Plot and Dark Pulse are pretty much mandatory here. Draco Meteor is to nuke a wall if it switches in when you set up a Nasty Plot, or if facing a Pokemon which could KO Hydreigon otherwise. The last moveslot is customisable. Belch is there because a Max-Ooze when dynamaxed surprises fairies, and gives you a special attack boost.
Hydreigon @ Leftovers
Ability: Levitate
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Nasty Plot
- Substitute
- Dark Pulse
- Flash Cannon
A little different. Use substitute in front of a wall which does not directly threaten you such as Corsola, Toxapex or Runerigus. When he switches out, decide whether you should Nasty Plot up, or just attack. Dark Pulse and Flash Cannon provide near perfect coverage. Just make sure to not use this recklessly, and beware of Infiltrator Dragapult which KOes through Substitute easily. A good late-game sweeper.
Hydreigon @ Life Orb/ Lum Berry
Ability: Levitate
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature/ Jolly Nature
- Dragon Dance
- Crunch
- Outrage/ Fire Fang/ Superpower
- Iron Tail/ Earthquake
The Dragon Dance set is pretty outclassed by Dragapult due to lower attack and speed, though the surprise factor may be useful in certain situations, such as when he expects you to go for Nasty Plot and switches into his Galarian Darmanitan, but you set up a Dragon Dance. Dragon Dance and Crunch are standard. Outrage with a Lum Berry is pretty powerful, with Iron Tail to smack any fairies which switch in. Fire Fang, Superpower and Earthquake are other options if needed.
Hydreigon may make good use of Choice items too, but in this meta you do not want to be locked into an undesirable move, since one turn can change the tide of the game. A scarf Hydreigon could surprise a Dragapult though.
Bulky sets are not very useful.
Fun fact: Hydreigon and Aegislash resist every types in the game between them.