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 (Grass)'s top six counters needs 0.79 trainers (round up: 1), and a mixed lobby of ranks 13-24 needs 0.98 (round up: 1). The raid timer is 180 seconds and one prepared trainer alone would take 2:19. A prepared solo becomes possible at level 25. A duo works from level 20.

Arceus (Grass) · Tier 3

grass

Weak to

flyingpoisonbugfireice

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 (Grass) 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(1.07)	2(1.21)	2(1.46)	3:32	6.0
Level 25	1(0.93)	1(1.00)	2(1.24)	2:55	5.9
Level 30	1(0.82)	1(0.88)	2(1.07)	2:34	5.4
Level 35	1(0.78)	1(0.83)	2(1.02)	2:26	5.2
Level 40	1(0.74)	1(0.79)	1(0.98)	2:19	4.9
Level 45	1(0.72)	1(0.76)	1(0.94)	2:13	4.5
Level 50	1(0.67)	1(0.72)	1(0.90)	2:07	4.0

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.

1 trainer at level 40

Kyurem (White)0.74

A prepared party

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

1 trainer at level 40

Kyurem (White)0.74
Blacephalon0.76
Eternatus0.79
Rayquaza0.80
Kyurem (Black)0.82
Reshiram0.84

A mixed local group

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

1 trainer at level 40

Toucannon0.95
Nihilego0.96
Zamazenta (Crowned Shield)0.96
Galarian Articuno0.99
Chandelure0.98
Cinderace0.98

The party these numbers assume

1. Kyurem (White)

Ice Fang + Ice Burn

2. Blacephalon

Incinerate + Mind Blown

3. Eternatus

Poison Jab + Dynamax Cannon

4. Rayquaza

Air Slash + Dragon Ascent

5. Kyurem (Black)

Dragon Tail + Freeze Shock

6. Reshiram

Fire Fang + Fusion Flare

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