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 — 2 if everyone is prepared

At level 40, a party of Thundurus (Therian)'s top six counters needs 1.90 trainers (round up: 2), and a mixed lobby of ranks 13-24 needs 2.52 (round up: 3). The raid timer is 300 seconds and one prepared trainer alone would take 8:44. No level in this range makes it soloable with a prepared party. A duo works from level 35.

Thundurus (Therian) · Tier 5

electricflying

Weak to

rockice

Boss CP: 50,369
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 Thundurus (Therian) 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(2.33)	3(2.98)	4(3.83)	13:43	6.0
Level 25	3(2.03)	3(2.50)	4(3.21)	11:30	6.0
Level 30	2(1.82)	3(2.17)	3(2.81)	10:00	6.0
Level 35	2(1.59)	2(1.99)	3(2.65)	9:10	5.9
Level 40	2(1.49)	2(1.90)	3(2.52)	8:44	5.9
Level 45	2(1.46)	2(1.81)	3(2.41)	8:18	5.9
Level 50	2(1.40)	2(1.75)	3(2.30)	8:03	5.8

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

Kyurem (White)1.49

A prepared party

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

2 trainers at level 40

Kyurem (White)1.49
Kyurem (Black)1.70
Eternatus1.98
Rhyperior2.02
Glimmora2.06
Necrozma (Dawn Wings)2.14

A mixed local group

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

3 trainers at level 40

Galarian Darmanitan (Standard)2.38
Mamoswine2.38
Tyrantrum2.41
Mewtwo2.42
Cetitan2.45
Landorus (Incarnate)2.49

The party these numbers assume

1. Kyurem (White)

Ice Fang + Ice Burn

2. Kyurem (Black)

Dragon Tail + Freeze Shock

3. Eternatus

Poison Jab + Dynamax Cannon

4. Rhyperior

Smack Down + Rock Wrecker

5. Glimmora

Rock Throw + Meteor Beam

6. Necrozma (Dawn Wings)

Psycho Cut + Moongeist Beam

See the full ranked counter list for Thundurus (Therian) · 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.