Using
Empoleon @ Assault Vest
Ability: Torrent
EVs: 252 HP / 252 Atk / 4 SpD
Careful Nature
IVs: 0 Spe
- Aqua Jet
- Earthquake
- Liquidation
- Avalanche
As the subject of my calculations, these happen:
+2 252 SpA Naganadel Devastating Drake (195 BP) vs. 252 HP / 4+ SpD Assault Vest Empoleon: 188-222 (50.5 - 59.6%) -- guaranteed 2HKO, meanwhile Empoleon does this afterwards: 252 Atk Empoleon Avalanche vs. 0 HP / 0 Def Naganadel: 258-304 (89.8 - 105.9%) -- 37.5% chance to OHKO.
Heatran is up next, and let's use this set:
Heatran @ Groundium Z
Ability: Flash Fire
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Magma Storm
- Earth Power
- Toxic
- Taunt
And going against the Empoleon set mentioned earlier, this happens: 252 SpA Heatran Earth Power vs. 252 HP / 4+ SpD Assault Vest Empoleon: 120-142 (32.2 - 38.1%) -- 96.4% chance to 3HKO, while in return, the damage done by Empoleon is phenomenal: 252 Atk Empoleon Earthquake vs. 0 HP / 0 Def Heatran: 316-372 (97.8 - 115.1%) -- 81.3% chance to OHKO, or a straight up 100% OHKO if you play with SR.
Blacephalon is a fun name, and with a typing of Fire/Ghost, it is a faster Chandelure. The set I'll be using was provided by the OU chat room on the showdown website itself:
Blacephalon @ Choice Specs
Ability: Beast Boost
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Shadow Ball
- Fire Blast
- Psyshock
- Trick
This gets us the most damage: 252 SpA Choice Specs Blacephalon Fire Blast vs. 252 HP / 4+ SpD Assault Vest Empoleon: 181-214 (48.6 - 57.5%) -- 94.5% chance to 2HKO.
In return, our boi can deliver a whopping: 252 Atk Empoleon Liquidation vs. 4 HP / 0 Def Blacephalon: 350-414 (141.1 - 166.9%) -- guaranteed OHKO. That is a lot of damage. Onwards to maybe the least unusual one on the list.
Ash Greninja! One of the fastest OU mons, outspeeding even Tapu Koko. The set I'll be using is the first set on the Analysis.
Greninja-Ash @ Choice Specs
Ability: Battle Bond
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Hydro Pump
- Dark Pulse
- Water Shuriken
- Spikes
By using Dark Pulse, the only non-resisted move, this happens: 252 SpA Choice Specs Greninja-Ash Dark Pulse vs. 252 HP / 4+ SpD Assault Vest Empoleon: 133-157 (35.7 - 42.2%) -- guaranteed 3HKO. The damage done back isn't that cool either: 252 Atk Empoleon Earthquake vs. 0 HP / 4 Def Greninja-Ash: 114-135 (40 - 47.3%) -- guaranteed 3HKO.
This is why I think that Empoleon should be a physical attacker on the Compendum.