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 5 to be safe — 4 if everyone is prepared

At level 40, a party of Mega Starmie's top six counters needs 3.58 trainers (round up: 4), and a mixed lobby of ranks 13-24 needs 4.17 (round up: 5). The raid timer is 300 seconds and one prepared trainer alone would take 16:39. No level in this range makes it soloable with a prepared party.

Mega Starmie · Mega Legendary

waterpsychic

Weak to

bugghostgrasselectricdark

Boss CP: 68,183
Boss HP: 22,500
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	5(4.64)	6(5.41)	7(6.23)	25:08	6.0
Level 25	4(3.77)	5(4.50)	6(5.27)	20:55	6.0
Level 30	4(3.26)	4(3.99)	5(4.64)	18:33	6.0
Level 35	4(3.18)	4(3.77)	5(4.36)	17:31	6.0
Level 40	4(3.10)	4(3.58)	5(4.17)	16:39	5.9
Level 45	3(2.86)	4(3.46)	4(3.98)	16:04	5.9
Level 50	3(2.79)	4(3.36)	4(3.84)	15:37	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.

4 trainers at level 40

Necrozma (Dawn Wings)3.10

A prepared party

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

4 trainers at level 40

Necrozma (Dawn Wings)3.10
Kartana3.51
Zeraora3.59
Xurkitree3.67
Kyurem (Black)3.80
Zarude3.82

A mixed local group

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

5 trainers at level 40

Eternatus4.07
Tyranitar3.96
Raikou4.10
Gholdengo4.12
Rillaboom4.13
Sceptile4.19

The party these numbers assume

1. Necrozma (Dawn Wings)

Shadow Claw + Moongeist Beam

2. Kartana

Fury Cutter + Leaf Blade

3. Zeraora

Spark + Plasma Fists

4. Xurkitree

Thunder Shock + Discharge

5. Kyurem (Black)

Shadow Claw + Fusion Bolt

6. Zarude

Vine Whip + Power Whip

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.