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 Ampharos's top six counters needs 1.42 trainers (round up: 2), and a mixed lobby of ranks 13-24 needs 1.81 (round up: 2). The raid timer is 180 seconds and one prepared trainer alone would take 4:09. No level in this range makes it soloable with a prepared party. A duo works from level 25.

Ampharos · Shadow Tier 3

electric

Weak to

ground

Boss CP: 19,388
Boss HP: 4,000
Raid timer: 180s
Party used: 6

Trainers needed, by attacker level

Scroll sideways for the mixed-lobby column.

Trainers needed to beat Ampharos 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(1.85)	3(2.08)	3(2.60)	6:04	5.4
Level 25	2(1.49)	2(1.77)	3(2.26)	5:11	5.1
Level 30	2(1.40)	2(1.54)	3(2.00)	4:31	4.6
Level 35	2(1.32)	2(1.46)	2(1.91)	4:17	4.3
Level 40	2(1.27)	2(1.42)	2(1.81)	4:09	4.0
Level 45	2(1.23)	2(1.39)	2(1.75)	4:04	3.9
Level 50	2(1.12)	2(1.33)	2(1.69)	3:54	3.6

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)1.27

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)1.27
Groudon1.35
Eternatus1.39
Necrozma (Dawn Wings)1.49
Garchomp1.49
Landorus (Incarnate)1.53

A mixed local group

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

2 trainers at level 40

Krookodile1.71
Golurk1.75
Rhydon1.77
Baxcalibur1.78
Keldeo1.86
Mudsdale1.81

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. Necrozma (Dawn Wings)

Psycho Cut + Moongeist Beam

5. Garchomp

Mud Shot + Earth Power

6. Landorus (Incarnate)

Mud Shot + Earth Power

See the full ranked counter list for Ampharos · 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.