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 Blacephalon's top six counters needs 1.78 trainers (round up: 2), and a mixed lobby of ranks 13-24 needs 1.98 (round up: 2). The raid timer is 300 seconds and one prepared trainer alone would take 8:12. No level in this range makes it soloable with a prepared party. A duo works from level 35.

Blacephalon · Tier 5

fireghost

Weak to

groundrockghostwaterdark

Boss CP: 51,600
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 Blacephalon 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(3.28)	3(2.76)	4(3.15)	12:41	6.0
Level 25	3(2.45)	3(2.32)	3(2.53)	10:41	6.0
Level 30	3(2.12)	3(2.10)	3(2.23)	9:40	6.0
Level 35	3(2.02)	2(1.91)	3(2.08)	8:48	6.0
Level 40	2(1.70)	2(1.78)	2(1.98)	8:12	6.0
Level 45	2(1.67)	2(1.74)	2(1.90)	7:59	6.0
Level 50	2(1.61)	2(1.67)	2(1.82)	7:42	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.

2 trainers at level 40

Landorus (Therian)1.70

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)1.70
Inteleon1.74
Necrozma (Dawn Wings)1.86
Tyranitar1.78
Hydreigon1.81
Eternatus1.81

A mixed local group

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

2 trainers at level 40

Giratina (Origin)1.92
Greninja1.93
Kingler1.97
Hisuian Samurott1.95
Primarina1.97
Rampardos1.98

The party these numbers assume

1. Landorus (Therian)

Mud Shot + Sandsear Storm

2. Inteleon

Water Gun + Hydro Cannon

3. Necrozma (Dawn Wings)

Psycho Cut + Moongeist Beam

4. Tyranitar

Bite + Brutal Swing

5. Hydreigon

Bite + Brutal Swing

6. Eternatus

Dragon Tail + Dynamax Cannon

See the full ranked counter list for Blacephalon · 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.