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 — 2 if everyone is prepared

At level 40, a party of Yamper's top six counters needs 1.90 trainers (round up: 2), and a mixed lobby of ranks 13-24 needs 2.36 (round up: 3). The raid timer is 300 seconds and one prepared trainer alone would take 8:44. No level in this range makes it soloable with a prepared party. A duo works from level 35.

Yamper · Elite

electric

Weak to

ground

Boss CP: 13,766
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 Yamper 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	3(2.32)	3(2.58)	4(3.31)	11:53	5.5
Level 25	3(2.01)	3(2.28)	3(2.87)	10:30	4.9
Level 30	2(1.79)	3(2.06)	3(2.59)	9:29	4.2
Level 35	2(1.74)	2(1.98)	3(2.46)	9:06	3.9
Level 40	2(1.69)	2(1.90)	3(2.36)	8:44	3.6
Level 45	2(1.58)	2(1.83)	3(2.29)	8:25	3.4
Level 50	2(1.56)	2(1.78)	3(2.21)	8:12	3.1

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

Landorus (Therian)1.69

A prepared party

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

2 trainers at level 40

Landorus (Therian)1.69
Groudon1.82
Eternatus1.89
Excadrill1.98
Garchomp2.00
Mamoswine2.02

A mixed local group

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

3 trainers at level 40

Rhydon2.24
Keldeo2.29
Golurk2.29
Kyurem (White)2.30
Blacephalon2.32
Mudsdale2.37

The party these numbers assume

1. Landorus (Therian)

Mud Shot + Sandsear Storm

2. Groudon

Mud Shot + Precipice Blades

3. Eternatus

Poison Jab + Dynamax Cannon

4. Excadrill

Mud-Slap + Scorching Sands

5. Garchomp

Mud Shot + Earth Power

6. Mamoswine

Mud-Slap + High Horsepower

See the full ranked counter list for Yamper · 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.