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 5 to be safe — 4 if everyone is prepared

At level 40, a party of Mega Blastoise's top six counters needs 3.89 trainers (round up: 4), and a mixed lobby of ranks 13-24 needs 4.70 (round up: 5). The raid timer is 300 seconds and one prepared trainer alone would take 18:05. No level in this range makes it soloable with a prepared party.

Mega Blastoise · Mega Legendary

water

Weak to

grasselectric

Boss CP: 66,434
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 Blastoise 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	8(7.08)	7(6.83)	8(7.52)	31:45	6.0
Level 25	6(5.39)	6(5.51)	6(5.98)	25:36	6.0
Level 30	5(4.11)	5(4.42)	6(5.16)	20:33	6.0
Level 35	4(3.93)	5(4.15)	5(4.97)	19:17	6.0
Level 40	4(3.75)	4(3.89)	5(4.70)	18:05	6.0
Level 45	4(3.65)	4(3.77)	5(4.50)	17:32	6.0
Level 50	4(3.49)	4(3.63)	5(4.35)	16:52	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.

4 trainers at level 40

Zeraora3.75

A prepared party

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

4 trainers at level 40

Zeraora3.75
Kartana3.80
Xurkitree3.82
Thundurus (Therian)3.85
Zekrom4.05
Eternatus4.07

A mixed local group

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

5 trainers at level 40

Raikou4.55
Magnezone4.57
Kyurem (Black)4.59
Zapdos4.61
Necrozma (Dawn Wings)4.63
Decidueye4.69

The party these numbers assume

1. Zeraora

Volt Switch + Plasma Fists

2. Kartana

Razor Leaf + Leaf Blade

3. Xurkitree

Thunder Shock + Discharge

4. Thundurus (Therian)

Volt Switch + Wildbolt Storm

5. Zekrom

Charge Beam + Fusion Bolt

6. Eternatus

Poison Jab + Dynamax Cannon

See the full ranked counter list for Mega Blastoise · 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.