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 Bastiodon's top six counters needs 1.77 trainers (round up: 2), and a mixed lobby of ranks 13-24 needs 2.20 (round up: 3). The raid timer is 300 seconds and one prepared trainer alone would take 8:08. No level in this range makes it soloable with a prepared party. A duo works from level 30.

Bastiodon · Tier 5

rocksteel

Weak to

fightinggroundwater

Boss CP: 23,160
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 Bastiodon 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(2.07)	3(2.45)	4(3.05)	11:17	6.0
Level 25	2(1.88)	3(2.16)	3(2.69)	9:56	5.7
Level 30	2(1.69)	2(1.94)	3(2.40)	8:55	5.3
Level 35	2(1.62)	2(1.85)	3(2.29)	8:31	5.0
Level 40	2(1.51)	2(1.77)	3(2.20)	8:08	4.8
Level 45	2(1.47)	2(1.69)	3(2.13)	7:48	4.6
Level 50	2(1.44)	2(1.65)	3(2.06)	7:37	4.5

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

Keldeo1.51

A prepared party

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

2 trainers at level 40

Keldeo1.51
Lucario1.71
Landorus (Therian)1.76
Terrakion1.77
Blaziken1.85
Groudon2.01

A mixed local group

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

3 trainers at level 40

Kartana2.12
Marshadow2.13
Excadrill2.14
Mewtwo2.14
Mamoswine2.19
Garchomp2.19

The party these numbers assume

1. Keldeo

Low Kick + Secret Sword

2. Lucario

Force Palm + Aura Sphere

3. Landorus (Therian)

Mud Shot + Sandsear Storm

4. Terrakion

Double Kick + Sacred Sword

5. Blaziken

Counter + Aura Sphere

6. Groudon

Mud Shot + Precipice Blades

See the full ranked counter list for Bastiodon · 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.