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 2 to be safe — 2 if everyone is prepared

At level 40, a party of Castform (Sunny)'s top six counters needs 1.65 trainers (round up: 2), and a mixed lobby of ranks 13-24 needs 1.87 (round up: 2). The raid timer is 300 seconds and one prepared trainer alone would take 7:35. No level in this range makes it soloable with a prepared party. A duo works from level 30.

Castform (Sunny) · Tier 5

fire

Weak to

groundrockwater

Boss CP: 23,405
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 Castform (Sunny) 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(2.24)	3(2.37)	3(2.91)	10:55	6.0
Level 25	2(1.95)	3(2.06)	3(2.42)	9:30	5.8
Level 30	2(1.70)	2(1.87)	3(2.06)	8:36	5.7
Level 35	2(1.58)	2(1.76)	2(1.95)	8:07	5.5
Level 40	2(1.54)	2(1.65)	2(1.87)	7:35	5.4
Level 45	2(1.49)	2(1.59)	2(1.81)	7:20	5.4
Level 50	2(1.40)	2(1.51)	2(1.76)	6:58	5.3

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

Landorus (Therian)1.54

A prepared party

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

2 trainers at level 40

Landorus (Therian)1.54
Inteleon1.65
Glimmora1.65
Kyogre1.67
Eternatus1.68
Groudon1.70

A mixed local group

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

2 trainers at level 40

Rhyperior1.80
Gigalith1.82
Garchomp1.84
Necrozma (Dawn Wings)1.84
Terrakion1.86
Landorus (Incarnate)1.86

The party these numbers assume

1. Landorus (Therian)

Mud Shot + Sandsear Storm

2. Inteleon

Water Gun + Hydro Cannon

3. Glimmora

Rock Throw + Meteor Beam

4. Kyogre

Waterfall + Origin Pulse

5. Eternatus

Poison Jab + Dynamax Cannon

6. Groudon

Mud Shot + Precipice Blades

See the full ranked counter list for Castform (Sunny) · 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.