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 Yamask's top six counters needs 2.79 trainers (round up: 3), and a mixed lobby of ranks 13-24 needs 3.19 (round up: 4). The raid timer is 300 seconds and one prepared trainer alone would take 13:09. No level in this range makes it soloable with a prepared party.

Yamask · Shadow Tier 5

ghost

Weak to

ghostdark

Boss CP: 16,826
Boss HP: 15,000
Raid timer: 300s
Party used: 6

Trainers needed, by attacker level

Scroll sideways for the mixed-lobby column.

Trainers needed to beat Yamask 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(3.90)	5(4.12)	5(4.55)	19:29	5.9
Level 25	3(2.88)	4(3.47)	4(3.86)	16:23	5.8
Level 30	3(2.52)	4(3.03)	4(3.45)	14:18	5.6
Level 35	3(2.40)	3(2.90)	4(3.30)	13:42	5.4
Level 40	3(2.31)	3(2.79)	4(3.19)	13:09	5.4
Level 45	3(2.29)	3(2.71)	4(3.07)	12:49	5.2
Level 50	3(2.18)	3(2.64)	3(2.95)	12:29	5.1

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

Necrozma (Dawn Wings)2.31

A prepared party

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

3 trainers at level 40

Necrozma (Dawn Wings)2.31
Darkrai2.68
Blacephalon2.89
Kyurem (Black)2.90
Hydreigon2.96
Lunala2.97

A mixed local group

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

4 trainers at level 40

Gengar3.12
Gholdengo3.12
Kingambit3.14
Hoopa (Unbound)3.16
Hisuian Zoroark3.19
Weavile3.18

The party these numbers assume

1. Necrozma (Dawn Wings)

Psycho Cut + Moongeist Beam

2. Darkrai

Snarl + Foul Play

3. Blacephalon

Astonish + Shadow Ball

4. Kyurem (Black)

Shadow Claw + Freeze Shock

5. Hydreigon

Bite + Brutal Swing

6. Lunala

Shadow Claw + Shadow Ball

See the full ranked counter list for Yamask · 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.