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 1 to be safe — 1 if everyone is prepared

At level 40, a party of Rotom (Wash)'s top six counters needs 0.83 trainers (round up: 1), and a mixed lobby of ranks 13-24 needs 0.98 (round up: 1). The raid timer is 180 seconds and one prepared trainer alone would take 2:26. A prepared solo becomes possible at level 30. A duo works from level 20.

Rotom (Wash) · Tier 3

electricwater

Weak to

groundgrass

Boss CP: 20,100
Boss HP: 3,600
Raid timer: 180s
Party used: 6

Trainers needed, by attacker level

Scroll sideways for the mixed-lobby column.

Trainers needed to beat Rotom (Wash) 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	2(1.09)	2(1.22)	2(1.39)	3:34	5.5
Level 25	1(0.94)	2(1.03)	2(1.22)	3:02	5.0
Level 30	1(0.84)	1(0.91)	2(1.08)	2:40	4.3
Level 35	1(0.80)	1(0.88)	2(1.02)	2:34	4.0
Level 40	1(0.76)	1(0.83)	1(0.98)	2:26	3.6
Level 45	1(0.73)	1(0.80)	1(0.94)	2:21	3.3
Level 50	1(0.72)	1(0.77)	1(0.90)	2:16	3.0

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.

1 trainer at level 40

Kartana0.76

A prepared party

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

1 trainer at level 40

Kartana0.76
Landorus (Therian)0.78
Shaymin (Sky)0.82
Groudon0.86
Zarude0.89
Xurkitree0.88

A mixed local group

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

1 trainer at level 40

Tapu Bulu0.94
Excadrill0.94
Mamoswine0.95
Decidueye0.95
Breloom0.96
Garchomp0.96

The party these numbers assume

1. Kartana

Razor Leaf + Leaf Blade

2. Landorus (Therian)

Mud Shot + Sandsear Storm

3. Shaymin (Sky)

Magical Leaf + Grass Knot

4. Groudon

Mud Shot + Precipice Blades

5. Zarude

Vine Whip + Power Whip

6. Xurkitree

Thunder Shock + Power Whip

See the full ranked counter list for Rotom (Wash) · 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.