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 Forretress's top six counters needs 1.00 trainers (round up: 2), and a mixed lobby of ranks 13-24 needs 1.18 (round up: 2). The raid timer is 180 seconds and one prepared trainer alone would take 2:56. A prepared solo becomes possible at level 45. A duo works from level 20.

Forretress · Shadow Tier 3

bugsteel

Weak to

fire

Boss CP: 16,510
Boss HP: 4,000
Raid timer: 180s
Party used: 6

Trainers needed, by attacker level

Scroll sideways for the mixed-lobby column.

Trainers needed to beat Forretress 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	2(1.32)	2(1.47)	2(1.80)	4:19	5.8
Level 25	2(1.08)	2(1.27)	2(1.51)	3:43	5.5
Level 30	2(1.01)	2(1.13)	2(1.32)	3:19	5.2
Level 35	1(0.94)	2(1.06)	2(1.25)	3:06	4.8
Level 40	1(0.91)	2(1.00)	2(1.18)	2:56	4.7
Level 45	1(0.84)	1(0.95)	2(1.14)	2:47	4.4
Level 50	1(0.81)	1(0.92)	2(1.10)	2:42	4.1

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

Blacephalon0.91

A prepared party

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

2 trainers at level 40

Blacephalon0.91
Reshiram0.92
Volcarona1.03
Heatran1.04
Cinderace1.05
Blaziken1.06

A mixed local group

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

2 trainers at level 40

Incineroar1.12
Charizard1.14
Entei1.15
Infernape1.14
Flareon1.15
Volcanion1.16

The party these numbers assume

1. Blacephalon

Incinerate + Mind Blown

2. Reshiram

Fire Fang + Fusion Flare

3. Volcarona

Fire Spin + Overheat

4. Heatran

Fire Spin + Magma Storm

5. Cinderace

Fire Spin + Pyroball

6. Blaziken

Fire Spin + Blast Burn

See the full ranked counter list for Forretress · 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.