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 Tapu Koko's top six counters needs 2.12 trainers (round up: 3), and a mixed lobby of ranks 13-24 needs 2.59 (round up: 3). The raid timer is 300 seconds and one prepared trainer alone would take 9:46. No level in this range makes it soloable with a prepared party. A duo works from level 50.

Tapu Koko · Tier 5

electricfairy

Weak to

poisonground

Boss CP: 45,438
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 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	3(2.70)	4(3.14)	5(4.06)	14:26	6.0
Level 25	3(2.41)	3(2.65)	4(3.27)	12:12	6.0
Level 30	3(2.12)	3(2.34)	3(2.87)	10:47	6.0
Level 35	3(2.05)	3(2.21)	3(2.73)	10:09	6.0
Level 40	2(1.96)	3(2.12)	3(2.59)	9:46	5.9
Level 45	2(1.87)	3(2.03)	3(2.50)	9:21	5.9
Level 50	2(1.83)	2(1.99)	3(2.40)	9:10	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

Eternatus1.96

A prepared party

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

3 trainers at level 40

Eternatus1.96
Landorus (Therian)2.05
Groudon2.10
Nihilego2.19
Naganadel2.22
Zacian (Crowned Sword)2.22

A mixed local group

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

3 trainers at level 40

Rhyperior2.43
Landorus (Incarnate)2.43
Regigigas2.51
Overqwil2.56
Roserade2.60
Gengar2.58

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. Zacian (Crowned Sword)

Metal Claw + Behemoth Blade

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.