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 6 to be safe — 5 if everyone is prepared

At level 40, a party of Arceus's top six counters needs 4.25 trainers (round up: 5), and a mixed lobby of ranks 13-24 needs 5.43 (round up: 6). The raid timer is 300 seconds and one prepared trainer alone would take 19:34. No level in this range makes it soloable with a prepared party.

Arceus · Elite

normal

Weak to

fighting

Boss CP: 56,910
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 Arceus 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	7(6.50)	7(6.85)	10(9.14)	31:32	6.0
Level 25	7(6.01)	7(6.08)	8(7.38)	28:00	6.0
Level 30	5(4.15)	5(4.92)	7(6.29)	22:39	6.0
Level 35	4(3.60)	5(4.53)	6(5.76)	20:51	6.0
Level 40	4(3.43)	5(4.25)	6(5.43)	19:34	6.0
Level 45	4(3.37)	5(4.12)	6(5.21)	18:56	6.0
Level 50	4(3.30)	4(3.97)	5(4.97)	18:17	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.

4 trainers at level 40

Keldeo3.43

A prepared party

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

5 trainers at level 40

Keldeo3.43
Lucario4.14
Terrakion4.21
Kartana4.35
Zamazenta (Crowned Shield)4.63
Necrozma (Dusk Mane)4.76

A mixed local group

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

6 trainers at level 40

Gallade5.18
Marshadow5.14
Mewtwo5.23
Cobalion5.25
Virizion5.38
Hisuian Decidueye5.48

The party these numbers assume

1. Keldeo

Low Kick + Secret Sword

2. Lucario

Force Palm + Aura Sphere

3. Terrakion

Double Kick + Sacred Sword

4. Kartana

Fury Cutter + Sacred Sword

5. Zamazenta (Crowned Shield)

Metal Claw + Behemoth Bash

6. Necrozma (Dusk Mane)

Psycho Cut + Sunsteel Strike

See the full ranked counter list for Arceus · 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.