Hydreigon @ Life Orb
Trait: Levitate
EVs: 4 HP / 252 SpA / 252 Spe
Modest Nature (+SAtk, -Atk)
- Draco Meteor
- Fire Blast
- Focus Blast
- Dark Pulse / Taunt
Hydreigon should not be using a scarf or specs. This is really a simple wallbreaker set. Draco Meteor coming off of 383 SpA and a LO boost does absurd amounts of damage to those that don't resist it, and for those that do, Fire Blast and Focus Blast can help against those that resist it, like Heatran, Scizor, Ferrothorn, Tyranitar, and other friends. The last move is entirely a case of whether or not you want an easier time with a Jellicent/Ferrothorn core (Dark Pulse means you don't have to mindgame as much), or Blissey (Taunt means it can't heal after sponging a Meteor).
Bronzong @ Leftovers
Trait: Levitate
EVs: 252 HP / 84 Atk / 80 Def / 92 SpD
IVs: 2 Spe
Sassy Nature (+SDef, -Spd)
- Stealth Rock
- Gyro Ball
- Hidden Power [Ice]
- Earthquake
Bronzong can sync up well with our draconic hydra friend by sponging the Ice, Dragon, Bug, and to an extent, Fighting attacks aimed at Hydreigon. It can support a team as well by checking, or even countering threats like Excadrill, Landorus, and even Thundurus to an extent. Stealth Rock is nice, as it helps score some needed KOs, and the rest is simple enough. Gyro Ball cuts into everything that doesn't resist it and then some, as with a speed stat this low, it's probably going to hit everything very hard. Hidden Power Ice has it's niche in killing off Landorus, Gliscor, and other 4x Ice weaks (Salamence, Dragonite). Earthquake otherwise rounds off the set for good reason: To KO Excadrill after a Gyro Ball pops any potential Balloons.
This core overall hates Conkeldurr, Machamp, and arguably Lucario as well. Conkeldurr can KO Hydreigon at +1 with Mach Punch if it's taken any prior damage at all, and it can set up on Bronzong due to his low speed dropping Gyro Ball's power. Machamp is a bit rarer, but still does the same due to bullshit Dynamicpunch hax. Lucario may be a bit hard-pressed to set up, but he generally will outspeed both members of this core, and start KOing them.
For that reason, pairing this core up with a bulky Psychic is a good idea. Reuniclus stands out above the rest generally.