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 Greninja's top six counters needs 2.89 trainers (round up: 3), and a mixed lobby of ranks 13-24 needs 3.25 (round up: 4). The raid timer is 300 seconds and one prepared trainer alone would take 13:27. No level in this range makes it soloable with a prepared party.

Mega Greninja · Primal

waterdark

Weak to

fightingbuggrasselectricfairy

Boss CP: 65,771
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 Greninja 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(3.33)	5(4.32)	6(5.06)	20:04	6.0
Level 25	4(3.02)	4(3.73)	5(4.24)	17:20	6.0
Level 30	3(2.65)	4(3.22)	4(3.71)	14:59	6.0
Level 35	3(2.52)	4(3.05)	4(3.47)	14:11	6.0
Level 40	3(2.41)	3(2.89)	4(3.25)	13:27	6.0
Level 45	3(2.34)	3(2.78)	4(3.12)	12:55	6.0
Level 50	3(2.21)	3(2.65)	4(3.01)	12:19	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

Keldeo2.41

A prepared party

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

3 trainers at level 40

Keldeo2.41
Kartana2.81
Zeraora3.00
Zekrom3.03
Shaymin (Sky)3.07
Lucario3.04

A mixed local group

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

4 trainers at level 40

Xurkitree3.12
Terrakion3.11
Hisuian Decidueye3.23
Urshifu (Single Strike)3.24
Tapu Koko3.18
Zacian (Crowned Sword)3.24

The party these numbers assume

1. Keldeo

Low Kick + Secret Sword

2. Kartana

Fury Cutter + Sacred Sword

3. Zeraora

Volt Switch + Plasma Fists

4. Zekrom

Charge Beam + Fusion Bolt

5. Shaymin (Sky)

Magical Leaf + Grass Knot

6. Lucario

Force Palm + Aura Sphere

See the full ranked counter list for Mega Greninja · 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.