Weak toFighting ×1.6

Attacker	Type	Moveset	DPS
Lucario	FightingSteel	Force PalmAura SphereLegacy	37.4
Pheromosa	BugFighting	Low KickFocus Blast	34.2
Terrakion	RockFighting	Double KickSacred SwordLegacy	34.1
Blaziken	FireFighting	CounterAura Sphere	33.8
Kartana	GrassSteel	Fury CutterSacred Sword	32.3
Conkeldurr	Fighting	Force PalmFocus Blast	31.2
Keldeo	WaterFighting	Low KickSacred Sword	30.9
Breloom	GrassFighting	Force PalmDynamic Punch	30.8
Urshifu	Fighting	CounterDynamic Punch	30.6
Eternatus	PoisonDragon	Poison JabDynamax CannonLegacy	30.4
Marshadow	FightingGhost	CounterClose Combat	29.9
Mewtwo	Psychic	CounterFocus BlastLegacy	29.7

Overcast boosts the Fighting attacks above. Partly cloudy boosts Porygon-Z.

Level 40, 15 attack IV, costed against Porygon-Z's own defense and typing, one per evolution family.

Porygon-Z's moveset, CP and shiny All counters Raid board

Questions people ask

What is Porygon-Z weak to in Pokémon GO?

Porygon-Z takes 1.6 times from Fighting.

What's the best counter to Porygon-Z?

Lucario with Force Palm and Aura Sphere, worth 37.4 damage per second against Porygon-Z's own defense. The full ranking is above.