#0142 · Gen 1

Aerodactyl (Mega) — Best counters

Weaknesses

rock×1.60steel×1.60water×1.60electric×1.60ice×1.60

	Pokémon	Fast move	Charged move	Weather	Score
1	Regieleki	normalLock On	electricThunder CageELITE	Rainy · partial	10013.1
2	Kyogre (Primal)	waterWaterfall	waterOrigin PulseELITE	Rainy	9912.9
3	Metagross (Mega)	steelBullet Punch	steelMeteor MashELITE	Snow	8811.5
4	Diancie (Mega)	rockRock Throw	rockRock Slide	Partly Cloudy	8811.5
5	Manectric (Mega)	electricThunder Fang	electricWild Charge	Rainy	8411.0
6	Swampert (Mega)	waterWater Gun	waterHydro CannonELITE	Rainy	8310.9
7	Xurkitree	electricThunder Shock	electricDischarge	Rainy	8210.8
8	Kyurem (White)	iceIce Fang	iceBlizzard	Snow	8210.8
9	Ampharos (Mega)	electricVolt Switch	electricZap Cannon	Rainy	8010.5
10	Zekrom	electricCharge Beam	electricFusion BoltELITE	Rainy	7910.3
11	Deoxys (Attack)	psychicZen Headbutt	electricZap Cannon	Rainy · partial	7810.2
12	Tyranitar (Mega)	rockSmack DownELITE	rockStone Edge	Partly Cloudy	7810.2
13	Blastoise (Mega)	waterWater Gun	waterHydro CannonELITE	Rainy	7710.1
14	Gyarados (Mega)	waterWaterfall	waterHydro Pump	Rainy	7610.0
15	Sharpedo (Mega)	waterWaterfall	waterHydro Pump	Rainy	769.9
16	Kyogre	waterWaterfall	waterOrigin PulseELITE	Rainy	769.9
17	Metagross	steelBullet Punch	steelMeteor MashELITE	Snow	759.9
18	Aerodactyl (Mega)	rockRock Throw	rockRock Slide	Partly Cloudy	759.8
19	Rampardos	rockSmack Down	rockRock Slide	Partly Cloudy	749.7
20	Thundurus (Therian)	electricVolt Switch	electricThunderbolt	Rainy	749.6

Aerodactyl (Mega) is weak to Rock (×1.6), Steel (×1.6), Water (×1.6), Electric (×1.6), Ice (×1.6).
Watch its Steel/Dark/Rock/Normal/Ground moves — counters like Regieleki and Metagross (Mega) take super-effective damage from them.
Rainy weather boosts Electric moves ×1.2 — the best time to battle Aerodactyl (Mega).

Rankings are estimated cycle DPS (attack stat × move damage ÷ cycle time, with STAB and type effectiveness). Not a full battle simulation.