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 Cobalion's top six counters needs 3.90 trainers (round up: 4), and a mixed lobby of ranks 13-24 needs 4.72 (round up: 5). The raid timer is 300 seconds and one prepared trainer alone would take 17:58. No level in this range makes it soloable with a prepared party.

Cobalion · Elite

steelfighting

Weak to

fightinggroundfire

Boss CP: 45,727
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 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	5(4.54)	7(6.07)	8(7.29)	27:56	6.0
Level 25	5(4.10)	5(5.00)	7(6.17)	23:00	6.0
Level 30	4(3.55)	5(4.28)	6(5.28)	19:42	6.0
Level 35	4(3.43)	5(4.06)	5(4.97)	18:40	6.0
Level 40	4(3.28)	4(3.90)	5(4.72)	17:58	6.0
Level 45	4(3.18)	4(3.78)	5(4.49)	17:23	6.0
Level 50	4(3.10)	4(3.59)	5(4.34)	16:31	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.

4 trainers at level 40

Keldeo3.28

A prepared party

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

4 trainers at level 40

Keldeo3.28
Terrakion3.94
Reshiram3.97
Blaziken4.11
Landorus (Therian)4.13
Blacephalon4.00

A mixed local group

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

5 trainers at level 40

Heatran4.58
Cinderace4.55
Raikou4.63
Ho-Oh4.63
Delphox4.66
Chandelure4.66

The party these numbers assume

1. Keldeo

Low Kick + Secret Sword

2. Terrakion

Double Kick + Sacred Sword

3. Reshiram

Fire Fang + Fusion Flare

4. Blaziken

Counter + Aura Sphere

5. Landorus (Therian)

Mud Shot + Sandsear Storm

6. Blacephalon

Incinerate + Mind Blown

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.