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 1 to be safe — 1 if everyone is prepared

At level 40, a party of Ampharos's top six counters needs 0.69 trainers (round up: 1), and a mixed lobby of ranks 13-24 needs 0.89 (round up: 1). The raid timer is 180 seconds and one prepared trainer alone would take 2:02. A prepared solo becomes possible at level 20. A duo works from level 20.

Ampharos · Tier 3

electric

Weak to

ground

Boss CP: 18,393
Boss HP: 3,600
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	1(0.85)	1(0.97)	2(1.29)	2:51	4.5
Level 25	1(0.77)	1(0.86)	2(1.10)	2:31	3.7
Level 30	1(0.65)	1(0.77)	1(0.98)	2:15	2.7
Level 35	1(0.64)	1(0.73)	1(0.93)	2:07	2.3
Level 40	1(0.62)	1(0.69)	1(0.89)	2:02	2.1
Level 45	1(0.58)	1(0.68)	1(0.84)	1:59	2.0
Level 50	1(0.55)	1(0.65)	1(0.82)	1:55	1.7

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.

1 trainer at level 40

Landorus (Therian)0.62

A prepared party

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

1 trainer at level 40

Landorus (Therian)0.62
Groudon0.68
Eternatus0.68
Excadrill0.72
Necrozma (Dawn Wings)0.72
Garchomp0.73

A mixed local group

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

1 trainer at level 40

Keldeo0.84
Golurk0.85
Kyurem (White)0.86
Mudsdale0.87
Rhydon0.86
Donphan0.88

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. Necrozma (Dawn Wings)

Psycho Cut + Moongeist Beam

6. Garchomp

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.