Weak toFightingGroundRockWater ×1.6

Attacker	Type	Moveset	DPS
Lucario	FightingSteel	Force PalmAura SphereLegacy	29.5
Pheromosa	BugFighting	Low KickFocus Blast	27.0
Terrakion	RockFighting	Double KickSacred SwordLegacy	26.9
Blaziken	FireFighting	CounterAura Sphere	26.7
Kartana	GrassSteel	Fury CutterSacred Sword	25.5
Inteleon	Water	Water GunHydro CannonLegacy	25.4
Kyogre	Water	WaterfallOrigin PulseLegacy	25.4
Glimmora	RockPoison	Rock ThrowMeteor Beam	25.0
Groudon	Ground	Mud ShotPrecipice BladesLegacy	24.9
Rampardos	Rock	Smack DownRock Slide	24.8
Conkeldurr	Fighting	Force PalmFocus Blast	24.6
Keldeo	WaterFighting	Low KickSacred Sword	24.4

Overcast boosts the Fighting attacks above. Clear and Fog boost Mega Houndoom.

Level 40, 15 attack IV, costed against Mega Houndoom's own defense and typing, one per evolution family.

Mega Houndoom's moveset, stats and CP All counters Raid board

Questions people ask

What is Mega Houndoom weak to in Pokémon GO?

Mega Houndoom takes 1.6 times from Fighting, Ground, Rock and Water.

What's the best counter to Mega Houndoom?

Lucario with Force Palm and Aura Sphere, worth 29.5 damage per second against Mega Houndoom's own defense. The full ranking is above.