Group size estimator

How many trainers do I need to invite?

The Estimator is already "trainers of this attacker needed to finish inside the timer", so this page does not invent a number: it reads it off the boss's own ranked counter list for three realistic parties and re-simulates each of them at every level from 20 to 50.

Raid bossTierIVsWeatherFriendshipDodgingShadow attackersMega attackersLegendary attackers

Invite 4 to be safe — 3 if everyone is prepared

At level 40, a party of Mega Rayquaza's top six counters needs 2.71 trainers (round up: 3), and a mixed lobby of ranks 13-24 needs 3.43 (round up: 4). The raid timer is 300 seconds and one prepared trainer alone would take 12:35. No level in this range makes it soloable with a prepared party.

Mega Rayquaza · Mega Legendary

dragonflying

Weak to

icerockdragonfairy

Boss CP: 88,200
Boss HP: 22,500
Raid timer: 300s
Party used: 6

Trainers needed, by attacker level

Scroll sideways for the mixed-lobby column.

Trainers needed to beat Mega Rayquaza at each attacker level
Attacker level	Six of the best counter	A prepared party	A mixed local group	Prepared solo time	Faints per timer
Level 20	4(3.37)	5(4.66)	6(5.62)	21:41	6.0
Level 25	3(2.81)	4(3.95)	5(4.55)	18:21	6.0
Level 30	3(2.51)	4(3.28)	4(3.87)	15:14	6.0
Level 35	3(2.42)	3(2.99)	4(3.63)	13:53	6.0
Level 40	3(2.34)	3(2.71)	4(3.43)	12:35	6.0
Level 45	2(1.90)	3(2.51)	4(3.27)	11:41	6.0
Level 50	2(1.73)	3(2.40)	4(3.16)	11:10	6.0

Whole trainers in bold, the raw estimator in brackets — 2.04 means two trainers is right on the line and three is comfortable.

Six of the best counter

Every trainer brings six copies of the single best counter — the theoretical floor.

3 trainers at level 40

Kyurem (White)2.34

A prepared party

Each trainer brings the boss's top six counters, powered up and correctly TM'd.

3 trainers at level 40

Kyurem (White)2.34
Eternatus2.51
Mamoswine2.67
Glaceon2.86
Cetitan2.87
Weavile2.99

A mixed local group

Ranks 13-24: reasonable but unoptimised parties, which is what a public lobby usually is.

4 trainers at level 40

Zamazenta (Crowned Shield)3.25
Galarian Darmanitan (Standard)3.24
Avalugg3.26
Articuno3.36
Beartic3.41
Zacian (Crowned Sword)3.40

The party these numbers assume

1. Kyurem (White)

Ice Fang + Ice Burn

2. Eternatus

Dragon Tail + Dynamax Cannon

3. Mamoswine

Powder Snow + Avalanche

4. Glaceon

Frost Breath + Avalanche

5. Cetitan

Ice Shard + Avalanche

6. Weavile

Ice Shard + Triple Axel

See the full ranked counter list for Mega Rayquaza · check a real lobby (win chance, who brings what) · make a share card of the top six

How this is worked out

The boss is ranked once at level 40 with rankCached (the same memoised call /raids makes), then the three bands — rank 1, ranks 1-6, ranks 13-24 — are re-simulated at each attacker level with an 8-run Monte Carlo each. Holding the party fixed and moving only its level is deliberate: it answers "what if my party were level 20" rather than "what would a level-20 player's completely different party be", and it is about ten times cheaper than re-ranking every attacker seven times. The Estimator itself is Pokebattler's definition, time to win including rejoin time divided by the raid timer.