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 Swellow's top six counters needs 0.44 trainers (round up: 1), and a mixed lobby of ranks 13-24 needs 0.56 (round up: 1). The raid timer is 180 seconds and one prepared trainer alone would take 1:17. A prepared solo becomes possible at level 20. A duo works from level 20.

Swellow · Tier 3

normalflying

Weak to

rockelectricice

Boss CP: 14,147
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 Swellow 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(0.53)	1(0.62)	1(0.80)	1:48	4.0
Level 25	1(0.48)	1(0.55)	1(0.69)	1:36	3.1
Level 30	1(0.43)	1(0.48)	1(0.61)	1:25	2.2
Level 35	1(0.41)	1(0.47)	1(0.58)	1:22	1.9
Level 40	1(0.40)	1(0.44)	1(0.56)	1:17	1.6
Level 45	1(0.39)	1(0.43)	1(0.54)	1:15	1.5
Level 50	1(0.37)	1(0.42)	1(0.52)	1:13	1.5

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.

1 trainer at level 40

Kyurem (White)0.40

A prepared party

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

1 trainer at level 40

Kyurem (White)0.40
Regieleki0.42
Kyurem (Black)0.45
Thundurus (Therian)0.44
Xurkitree0.45
Zeraora0.46

A mixed local group

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

1 trainer at level 40

Necrozma (Dusk Mane)0.53
Raikou0.54
Zacian (Crowned Sword)0.55
Zapdos0.55
Magnezone0.56
Baxcalibur0.56

The party these numbers assume

1. Kyurem (White)

Ice Fang + Ice Burn

2. Regieleki

Lock-On + Thunder Cage

3. Kyurem (Black)

Dragon Tail + Freeze Shock

4. Thundurus (Therian)

Volt Switch + Wildbolt Storm

5. Xurkitree

Thunder Shock + Discharge

6. Zeraora

Spark + Plasma Fists

See the full ranked counter list for Swellow · 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.