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 1 to be safe — 1 if everyone is prepared

At level 40, a party of Arceus (Steel)'s top six counters needs 0.82 trainers (round up: 1), and a mixed lobby of ranks 13-24 needs 0.99 (round up: 1). The raid timer is 180 seconds and one prepared trainer alone would take 2:23. A prepared solo becomes possible at level 30. A duo works from level 20.

Arceus (Steel) · Tier 3

steel

Weak to

fightinggroundfire

Boss CP: 24,145
Boss HP: 3,600
Raid timer: 180s
Party used: 6

Trainers needed, by attacker level

Scroll sideways for the mixed-lobby column.

Trainers needed to beat Arceus (Steel) 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(1.11)	2(1.24)	2(1.52)	3:37	6.0
Level 25	1(0.91)	2(1.03)	2(1.26)	3:00	6.0
Level 30	1(0.77)	1(0.90)	2(1.12)	2:38	5.6
Level 35	1(0.75)	1(0.86)	2(1.05)	2:31	5.4
Level 40	1(0.74)	1(0.82)	1(0.99)	2:23	5.1
Level 45	1(0.73)	1(0.78)	1(0.97)	2:17	4.8
Level 50	1(0.64)	1(0.74)	1(0.93)	2:10	4.4

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

Keldeo0.74

A prepared party

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

1 trainer at level 40

Keldeo0.74
Blacephalon0.76
Lucario0.82
Terrakion0.83
Reshiram0.85
Landorus (Therian)0.90

A mixed local group

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

1 trainer at level 40

Chandelure0.98
Urshifu (Rapid Strike)0.98
Excadrill0.98
Volcarona0.99
Conkeldurr0.98
Gallade0.99

The party these numbers assume

1. Keldeo

Low Kick + Secret Sword

2. Blacephalon

Incinerate + Mind Blown

3. Lucario

Force Palm + Aura Sphere

4. Terrakion

Double Kick + Sacred Sword

5. Reshiram

Fire Fang + Fusion Flare

6. Landorus (Therian)

Mud Shot + Sandsear Storm

See the full ranked counter list for Arceus (Steel) · 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.