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 1 to be safe — 1 if everyone is prepared

At level 40, a party of Koraidon's top six counters needs 0.60 trainers (round up: 1), and a mixed lobby of ranks 13-24 needs 0.75 (round up: 1). The raid timer is 180 seconds and one prepared trainer alone would take 1:46. A prepared solo becomes possible at level 20. A duo works from level 20.

Koraidon · Tier 3

fightingdragon

Weak to

fairyflyingpsychicicedragon

Boss CP: 25,732
Boss HP: 3,600
Raid timer: 180s
Party used: 6

Trainers needed, by attacker level

Scroll sideways for the mixed-lobby column.

Trainers needed to beat Koraidon 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	1(0.86)	1(0.90)	2(1.15)	2:38	4.8
Level 25	1(0.73)	1(0.75)	1(0.98)	2:12	3.9
Level 30	1(0.66)	1(0.67)	1(0.86)	1:57	3.2
Level 35	1(0.62)	1(0.63)	1(0.80)	1:50	2.8
Level 40	1(0.59)	1(0.60)	1(0.75)	1:46	2.5
Level 45	1(0.58)	1(0.58)	1(0.72)	1:41	2.3
Level 50	1(0.55)	1(0.56)	1(0.69)	1:38	2.0

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.

1 trainer at level 40

Zacian (Crowned Sword)0.59

A prepared party

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

1 trainer at level 40

Zacian (Crowned Sword)0.59
Eternatus0.58
Enamorus (Incarnate)0.58
Tapu Lele0.60
Enamorus (Therian)0.63
Xerneas0.62

A mixed local group

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

1 trainer at level 40

Hatterene0.71
Zacian0.71
Rayquaza0.73
Primarina0.72
Mewtwo0.74
Sylveon0.74

The party these numbers assume

1. Zacian (Crowned Sword)

Air Slash + Play Rough

2. Eternatus

Dragon Tail + Dynamax Cannon

3. Enamorus (Incarnate)

Fairy Wind + Dazzling Gleam

4. Tapu Lele

Confusion + Nature's Madness

5. Enamorus (Therian)

Fairy Wind + Dazzling Gleam

6. Xerneas

Geomancy + Moonblast

See the full ranked counter list for Koraidon · 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.