#0018 · Gen 1

Pidgeot (Mega) — Best counters

Weaknesses

	Pokémon	Fast move	Charged move	Weather	Score
1	Regieleki	normalLock On	electricThunder CageELITE	Rainy · partial	10013.3
2	Diancie (Mega)	rockRock Throw	rockRock Slide	Partly Cloudy	8611.5
3	Manectric (Mega)	electricThunder Fang	electricWild Charge	Rainy	8211.0
4	Xurkitree	electricThunder Shock	electricDischarge	Rainy	8110.8
5	Kyurem (White)	iceIce Fang	iceBlizzard	Snow	8110.8
6	Ampharos (Mega)	electricVolt Switch	electricZap Cannon	Rainy	7910.5
7	Zekrom	electricCharge Beam	electricFusion BoltELITE	Rainy	7810.3
8	Deoxys (Attack)	psychicZen Headbutt	electricZap Cannon	Rainy · partial	7710.2
9	Tyranitar (Mega)	rockSmack DownELITE	rockStone Edge	Partly Cloudy	7610.2
10	Aerodactyl (Mega)	rockRock Throw	rockRock Slide	Partly Cloudy	749.8
11	Rampardos	rockSmack Down	rockRock Slide	Partly Cloudy	729.7
12	Thundurus (Therian)	electricVolt Switch	electricThunderbolt	Rainy	729.6
13	Deoxys (Normal)	electricCharge Beam	electricThunderbolt	Rainy	699.2
14	Eternatus	poisonPoison Jab	dragonDynamax CannonELITE	Windy · partial	699.2
15	Kyurem (Black)	dragonDragon Tail	electricFusion Bolt	Rainy · partial	699.1
16	Tyrantrum	rockRock Throw	rockMeteor Beam	Partly Cloudy	679.0
17	Electivire	electricThunder Shock	electricWild Charge	Rainy	679.0
18	Zapdos	electricThunder ShockELITE	electricZap Cannon	Rainy	668.8
19	Baxcalibur	iceIce Fang	iceBlizzard	Snow	668.8
20	Regigigas	normalHidden Power	normalCrush GripELITE	Partly Cloudy	668.8

Pidgeot (Mega) is weak to Rock (×1.6), Electric (×1.6), Ice (×1.6).
Watch its Flying/Steel moves — counters like Diancie (Mega) and Kyurem (White) take super-effective damage from them.
Rainy weather boosts Electric moves ×1.2 — the best time to battle Pidgeot (Mega).

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