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 Silvally (Psychic)'s top six counters needs 0.73 trainers (round up: 1), and a mixed lobby of ranks 13-24 needs 0.83 (round up: 1). The raid timer is 180 seconds and one prepared trainer alone would take 2:08. A prepared solo becomes possible at level 25. A duo works from level 20.

Silvally (Psychic) · Tier 3

psychic

Weak to

bugghostdark

Boss CP: 18,651
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 Silvally (Psychic) 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	1(0.81)	2(1.02)	2(1.16)	3:00	5.1
Level 25	1(0.70)	1(0.90)	2(1.02)	2:38	4.1
Level 30	1(0.66)	1(0.81)	1(0.91)	2:22	3.1
Level 35	1(0.61)	1(0.77)	1(0.87)	2:16	2.9
Level 40	1(0.60)	1(0.73)	1(0.83)	2:08	2.3
Level 45	1(0.59)	1(0.71)	1(0.80)	2:05	2.1
Level 50	1(0.54)	1(0.68)	1(0.77)	2:00	1.9

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.

1 trainer at level 40

Necrozma (Dawn Wings)0.60

A prepared party

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

1 trainer at level 40

Necrozma (Dawn Wings)0.60
Blacephalon0.70
Darkrai0.73
Gengar0.78
Chandelure0.78
Dragapult0.79

A mixed local group

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

1 trainer at level 40

Kyurem (Black)0.81
Giratina (Origin)0.81
Pheromosa0.81
Absol0.83
Zacian (Crowned Sword)0.82
Gholdengo0.82

The party these numbers assume

1. Necrozma (Dawn Wings)

Shadow Claw + Moongeist Beam

2. Blacephalon

Astonish + Shadow Ball

3. Darkrai

Snarl + Foul Play

4. Gengar

Shadow Claw + Shadow Ball

5. Chandelure

Hex + Shadow Ball

6. Dragapult

Astonish + Shadow Ball

See the full ranked counter list for Silvally (Psychic) · 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.