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 3 to be safe — 3 if everyone is prepared

At level 40, a party of Jirachi's top six counters needs 2.15 trainers (round up: 3), and a mixed lobby of ranks 13-24 needs 2.61 (round up: 3). The raid timer is 300 seconds and one prepared trainer alone would take 9:53. No level in this range makes it soloable with a prepared party.

Jirachi · Tier 5

steelpsychic

Weak to

groundghostfiredark

Boss CP: 41,335
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 Jirachi 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	3(2.78)	4(3.44)	4(3.94)	15:49	6.0
Level 25	3(2.21)	3(2.70)	4(3.39)	12:24	6.0
Level 30	3(2.09)	3(2.41)	3(2.92)	11:06	5.9
Level 35	2(1.88)	3(2.25)	3(2.78)	10:21	5.9
Level 40	2(1.81)	3(2.15)	3(2.61)	9:53	5.9
Level 45	2(1.80)	3(2.09)	3(2.49)	9:36	5.9
Level 50	2(1.73)	3(2.02)	3(2.42)	9:18	5.9

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.

2 trainers at level 40

Necrozma (Dawn Wings)1.81

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)1.81
Blacephalon1.93
Reshiram2.12
Landorus (Therian)2.19
Darkrai2.41
Chandelure2.42

A mixed local group

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

3 trainers at level 40

Gholdengo2.54
Delphox2.57
Ho-Oh2.57
Tyranitar2.59
Moltres2.59
Hydreigon2.60

The party these numbers assume

1. Necrozma (Dawn Wings)

Shadow Claw + Moongeist Beam

2. Blacephalon

Astonish + Mind Blown

3. Reshiram

Fire Fang + Fusion Flare

4. Landorus (Therian)

Mud Shot + Sandsear Storm

5. Darkrai

Snarl + Foul Play

6. Chandelure

Fire Spin + Shadow Ball

See the full ranked counter list for Jirachi · 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.