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 — 2 if everyone is prepared

At level 40, a party of Mega Starmie's top six counters needs 1.41 trainers (round up: 2), and a mixed lobby of ranks 13-24 needs 1.65 (round up: 2). The raid timer is 300 seconds and one prepared trainer alone would take 6:33. No level in this range makes it soloable with a prepared party. A duo works from level 25.

Mega Starmie · Mega

waterpsychic

Weak to

bugghostgrasselectricdark

Boss CP: 43,123
Boss HP: 9,000
Raid timer: 300s
Party used: 6

Trainers needed, by attacker level

Scroll sideways for the mixed-lobby column.

Trainers needed to beat Mega Starmie 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(1.83)	3(2.20)	3(2.50)	10:12	6.0
Level 25	2(1.52)	2(1.80)	3(2.12)	8:23	6.0
Level 30	2(1.31)	2(1.58)	2(1.85)	7:19	6.0
Level 35	2(1.27)	2(1.47)	2(1.73)	6:49	6.0
Level 40	2(1.22)	2(1.41)	2(1.65)	6:33	6.0
Level 45	2(1.14)	2(1.35)	2(1.58)	6:17	6.0
Level 50	2(1.10)	2(1.31)	2(1.51)	6:05	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.

2 trainers at level 40

Necrozma (Dawn Wings)1.22

A prepared party

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

2 trainers at level 40

Necrozma (Dawn Wings)1.22
Kartana1.40
Regieleki1.43
Zeraora1.44
Xurkitree1.46
Kyurem (Black)1.50

A mixed local group

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

2 trainers at level 40

Tyranitar1.57
Eternatus1.62
Raikou1.63
Rillaboom1.65
Sceptile1.65
Gholdengo1.65

The party these numbers assume

1. Necrozma (Dawn Wings)

Shadow Claw + Moongeist Beam

2. Kartana

Fury Cutter + Leaf Blade

3. Regieleki

Thunder Shock + Thunder Cage

4. Zeraora

Spark + Plasma Fists

5. Xurkitree

Thunder Shock + Discharge

6. Kyurem (Black)

Shadow Claw + Fusion Bolt

See the full ranked counter list for Mega Starmie · 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.