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 5 to be safe — 4 if everyone is prepared

At level 40, a party of Ampharos's top six counters needs 3.45 trainers (round up: 4), and a mixed lobby of ranks 13-24 needs 4.39 (round up: 5). The raid timer is 300 seconds and one prepared trainer alone would take 15:54. No level in this range makes it soloable with a prepared party.

Ampharos · Elite

electric

Weak to

ground

Boss CP: 43,354
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 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	5(4.60)	6(5.11)	7(6.53)	23:31	6.0
Level 25	4(3.78)	5(4.27)	6(5.49)	19:38	5.9
Level 30	4(3.44)	4(3.81)	5(4.93)	17:32	5.8
Level 35	4(3.36)	4(3.67)	5(4.62)	16:54	5.7
Level 40	4(3.02)	4(3.45)	5(4.39)	15:54	5.6
Level 45	3(2.86)	4(3.33)	5(4.25)	15:18	5.6
Level 50	3(2.81)	4(3.21)	5(4.10)	14:46	5.5

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

Landorus (Therian)3.02

A prepared party

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

4 trainers at level 40

Landorus (Therian)3.02
Groudon3.35
Eternatus3.43
Garchomp3.58
Necrozma (Dawn Wings)3.63
Landorus (Incarnate)3.72

A mixed local group

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

5 trainers at level 40

Mudsdale4.30
Rhydon4.30
Donphan4.33
Mewtwo4.34
Golurk4.34
Keldeo4.46

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. Garchomp

Mud Shot + Earth Power

5. Necrozma (Dawn Wings)

Psycho Cut + Moongeist Beam

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.