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 3 to be safe — 3 if everyone is prepared

At level 40, a party of Primarina's top six counters needs 2.13 trainers (round up: 3), and a mixed lobby of ranks 13-24 needs 2.54 (round up: 3). The raid timer is 300 seconds and one prepared trainer alone would take 9:49. No level in this range makes it soloable with a prepared party. A duo works from level 50.

Primarina · Tier 5

waterfairy

Weak to

poisongrasselectric

Boss CP: 43,838
Boss HP: 15,000
Raid timer: 300s
Party used: 6

Trainers needed, by attacker level

Scroll sideways for the mixed-lobby column.

Trainers needed to beat Primarina 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	4(3.12)	4(3.40)	4(3.86)	15:40	6.0
Level 25	3(2.57)	3(2.82)	4(3.19)	12:59	6.0
Level 30	3(2.27)	3(2.41)	3(2.78)	11:06	6.0
Level 35	3(2.16)	3(2.27)	3(2.66)	10:26	6.0
Level 40	3(2.07)	3(2.13)	3(2.54)	9:49	6.0
Level 45	3(2.01)	3(2.05)	3(2.44)	9:25	6.0
Level 50	2(1.91)	2(1.97)	3(2.36)	9:04	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.

3 trainers at level 40

Kartana2.07

A prepared party

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

3 trainers at level 40

Kartana2.07
Eternatus2.08
Zeraora2.12
Xurkitree2.14
Regieleki2.18
Thundurus (Therian)2.22

A mixed local group

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

3 trainers at level 40

Zamazenta (Crowned Shield)2.44
Necrozma (Dusk Mane)2.48
Roserade2.48
Raikou2.49
Electivire2.49
Necrozma (Dawn Wings)2.51

The party these numbers assume

1. Kartana

Razor Leaf + Leaf Blade

2. Eternatus

Poison Jab + Sludge Bomb

3. Zeraora

Volt Switch + Plasma Fists

4. Xurkitree

Thunder Shock + Power Whip

5. Regieleki

Lock-On + Thunder Cage

6. Thundurus (Therian)

Volt Switch + Wildbolt Storm

See the full ranked counter list for Primarina · 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.