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 2 to be safe — 2 if everyone is prepared

At level 40, a party of Cleffa's top six counters needs 1.35 trainers (round up: 2), and a mixed lobby of ranks 13-24 needs 1.83 (round up: 2). The raid timer is 300 seconds and one prepared trainer alone would take 6:12. No level in this range makes it soloable with a prepared party. A duo works from level 20.

Cleffa · Elite

fairy

Weak to

poisonsteel

Boss CP: 12,340
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 Cleffa 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(1.49)	2(1.83)	3(2.52)	8:25	4.5
Level 25	2(1.30)	2(1.61)	3(2.21)	7:23	3.6
Level 30	2(1.19)	2(1.46)	3(2.01)	6:42	3.0
Level 35	2(1.14)	2(1.40)	2(1.93)	6:28	2.7
Level 40	2(1.09)	2(1.35)	2(1.83)	6:12	2.5
Level 45	2(1.05)	2(1.30)	2(1.78)	6:00	2.4
Level 50	2(1.02)	2(1.26)	2(1.74)	5:49	2.2

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.

2 trainers at level 40

Zacian (Crowned Sword)1.09

A prepared party

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

2 trainers at level 40

Zacian (Crowned Sword)1.09
Necrozma (Dusk Mane)1.12
Zamazenta (Crowned Shield)1.14
Eternatus1.51
Metagross1.57
Necrozma (Dawn Wings)1.65

A mixed local group

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

2 trainers at level 40

Dialga (Origin)1.75
Genesect1.79
Genesect (Burn)1.79
Genesect (Chill)1.79
Genesect (Douse)1.79
Genesect (Shock)1.79

The party these numbers assume

1. Zacian (Crowned Sword)

Metal Claw + Behemoth Blade

2. Necrozma (Dusk Mane)

Metal Claw + Sunsteel Strike

3. Zamazenta (Crowned Shield)

Metal Claw + Behemoth Bash

4. Eternatus

Poison Jab + Sludge Bomb

5. Metagross

Bullet Punch + Meteor Mash

6. Necrozma (Dawn Wings)

Metal Claw + Moongeist Beam

See the full ranked counter list for Cleffa · 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.