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 Tapu Koko's top six counters needs 3.59 trainers (round up: 4), and a mixed lobby of ranks 13-24 needs 4.44 (round up: 5). The raid timer is 300 seconds and one prepared trainer alone would take 16:31. No level in this range makes it soloable with a prepared party.

Tapu Koko · Elite

electricfairy

Weak to

poisonground

Boss CP: 52,467
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 Tapu Koko 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(4.65)	6(5.51)	8(7.16)	25:21	6.0
Level 25	5(4.03)	5(4.54)	6(5.86)	20:52	6.0
Level 30	4(3.68)	4(4.00)	5(4.96)	18:24	6.0
Level 35	4(3.43)	4(3.79)	5(4.65)	17:27	6.0
Level 40	4(3.30)	4(3.59)	5(4.44)	16:31	6.0
Level 45	4(3.11)	4(3.47)	5(4.28)	15:58	6.0
Level 50	4(3.02)	4(3.29)	5(4.10)	15:09	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

Eternatus3.30

A prepared party

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

4 trainers at level 40

Eternatus3.30
Landorus (Therian)3.44
Groudon3.61
Nihilego3.65
Naganadel3.75
Excadrill3.79

A mixed local group

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

5 trainers at level 40

Landorus (Incarnate)4.03
Necrozma (Dawn Wings)4.24
Overqwil4.29
Roserade4.32
Regigigas4.38
Kyurem (White)4.50

The party these numbers assume

1. Eternatus

Poison Jab + Sludge Bomb

2. Landorus (Therian)

Mud Shot + Sandsear Storm

3. Groudon

Mud Shot + Precipice Blades

4. Nihilego

Poison Jab + Sludge Bomb

5. Naganadel

Poison Jab + Sludge Bomb

6. Excadrill

Mud-Slap + Scorching Sands

See the full ranked counter list for Tapu Koko · 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.