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 — 4 if everyone is prepared

At level 40, a party of Zacian's top six counters needs 3.76 trainers (round up: 4), and a mixed lobby of ranks 13-24 needs 5.31 (round up: 6). The raid timer is 300 seconds and one prepared trainer alone would take 17:17. No level in this range makes it soloable with a prepared party.

Zacian · Elite

fairy

Weak to

poisonsteel

Boss CP: 60,270
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 Zacian 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(4.65)	6(5.67)	9(8.48)	26:05	6.0
Level 25	4(3.96)	5(4.78)	7(6.92)	22:00	6.0
Level 30	4(3.57)	5(4.22)	6(5.88)	19:26	6.0
Level 35	4(3.20)	4(3.93)	6(5.56)	18:06	6.0
Level 40	4(3.08)	4(3.76)	6(5.31)	17:17	6.0
Level 45	3(2.99)	4(3.62)	6(5.04)	16:40	6.0
Level 50	3(2.93)	4(3.52)	5(4.85)	16:12	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

Zacian (Crowned Sword)3.08

A prepared party

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

4 trainers at level 40

Zacian (Crowned Sword)3.08
Zamazenta (Crowned Shield)3.17
Necrozma (Dusk Mane)3.23
Eternatus4.12
Metagross4.32
Naganadel4.61

A mixed local group

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

6 trainers at level 40

Roserade5.04
Tinkaton5.03
Jirachi5.28
Genesect5.27
Genesect (Burn)5.27
Genesect (Chill)5.27

The party these numbers assume

1. Zacian (Crowned Sword)

Metal Claw + Behemoth Blade

2. Zamazenta (Crowned Shield)

Metal Claw + Behemoth Bash

3. Necrozma (Dusk Mane)

Metal Claw + Sunsteel Strike

4. Eternatus

Poison Jab + Sludge Bomb

5. Metagross

Bullet Punch + Meteor Mash

6. Naganadel

Poison Jab + Sludge Bomb

See the full ranked counter list for Zacian · 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.