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 — 3 if everyone is prepared

At level 40, a party of Cobalion's top six counters needs 2.27 trainers (round up: 3), and a mixed lobby of ranks 13-24 needs 2.78 (round up: 3). The raid timer is 300 seconds and one prepared trainer alone would take 10:27. No level in this range makes it soloable with a prepared party.

Cobalion · Tier 5

steelfighting

Weak to

fightinggroundfire

Boss CP: 39,601
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 Cobalion 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(2.70)	4(3.32)	5(4.39)	15:17	6.0
Level 25	3(2.47)	3(2.85)	4(3.56)	13:08	6.0
Level 30	3(2.12)	3(2.53)	4(3.10)	11:39	6.0
Level 35	3(2.04)	3(2.40)	3(2.91)	11:01	6.0
Level 40	2(2.00)	3(2.27)	3(2.78)	10:27	6.0
Level 45	2(1.94)	3(2.16)	3(2.67)	9:58	6.0
Level 50	2(1.89)	3(2.08)	3(2.56)	9:34	5.9

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

Keldeo2.00

A prepared party

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

3 trainers at level 40

Keldeo2.00
Blacephalon2.08
Reshiram2.35
Terrakion2.39
Landorus (Therian)2.41
Lucario2.40

A mixed local group

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

3 trainers at level 40

Volcarona2.68
Kartana2.72
Urshifu (Single Strike)2.72
Darmanitan (Standard)2.75
Cinderace2.75
Marshadow2.78

The party these numbers assume

1. Keldeo

Low Kick + Secret Sword

2. Blacephalon

Incinerate + Mind Blown

3. Reshiram

Fire Fang + Fusion Flare

4. Terrakion

Double Kick + Sacred Sword

5. Landorus (Therian)

Mud Shot + Sandsear Storm

6. Lucario

Force Palm + Aura Sphere

See the full ranked counter list for Cobalion · 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.