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 2 to be safe — 1 if everyone is prepared

At level 40, a party of Alolan Rattata's top six counters needs 0.85 trainers (round up: 1), and a mixed lobby of ranks 13-24 needs 1.10 (round up: 2). The raid timer is 300 seconds and one prepared trainer alone would take 3:55. A prepared solo becomes possible at level 30. A duo works from level 20.

Alolan Rattata · Elite

darknormal

Weak to

fightingbugfairy

Boss CP: 15,385
Boss HP: 20,000
Raid timer: 300s
Party used: 6

Trainers needed, by attacker level

Scroll sideways for the mixed-lobby column.

Trainers needed to beat Alolan Rattata 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(1.01)	2(1.20)	2(1.56)	5:31	5.9
Level 25	1(0.88)	2(1.04)	2(1.36)	4:46	5.7
Level 30	1(0.80)	1(0.93)	2(1.21)	4:18	5.4
Level 35	1(0.75)	1(0.88)	2(1.15)	4:04	5.1
Level 40	1(0.73)	1(0.85)	2(1.10)	3:55	4.8
Level 45	1(0.70)	1(0.82)	2(1.07)	3:46	4.5
Level 50	1(0.67)	1(0.79)	2(1.03)	3:39	4.3

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

Keldeo0.73

A prepared party

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

1 trainer at level 40

Keldeo0.73
Lucario0.80
Terrakion0.83
Blaziken0.87
Kartana0.92
Urshifu (Single Strike)0.95

A mixed local group

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

2 trainers at level 40

Machamp1.05
Galarian Zapdos1.07
Mewtwo1.07
Hariyama1.07
Hawlucha1.08
Buzzwole1.10

The party these numbers assume

1. Keldeo

Low Kick + Secret Sword

2. Lucario

Force Palm + Aura Sphere

3. Terrakion

Double Kick + Sacred Sword

4. Blaziken

Counter + Aura Sphere

5. Kartana

Fury Cutter + Sacred Sword

6. Urshifu (Single Strike)

Counter + Dynamic Punch

See the full ranked counter list for Alolan Rattata · 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.