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 — 1 if everyone is prepared

At level 40, a party of Mega Swampert's top six counters needs 0.98 trainers (round up: 1), and a mixed lobby of ranks 13-24 needs 1.21 (round up: 2). The raid timer is 300 seconds and one prepared trainer alone would take 4:32. A prepared solo becomes possible at level 40. A duo works from level 20.

Mega Swampert · Mega

waterground

Weak to

grass

Boss CP: 43,153
Boss HP: 9,000
Raid timer: 300s
Party used: 6

Trainers needed, by attacker level

Scroll sideways for the mixed-lobby column.

Trainers needed to beat Mega Swampert 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(1.37)	2(1.46)	2(1.86)	6:48	6.0
Level 25	2(1.18)	2(1.23)	2(1.57)	5:44	6.0
Level 30	1(0.99)	2(1.07)	2(1.35)	5:00	6.0
Level 35	1(0.95)	2(1.03)	2(1.28)	4:47	6.0
Level 40	1(0.91)	1(0.98)	2(1.21)	4:32	5.8
Level 45	1(0.88)	1(0.94)	2(1.17)	4:23	5.7
Level 50	1(0.84)	1(0.89)	2(1.13)	4:09	5.6

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

Shaymin (Sky)0.91

A prepared party

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

1 trainer at level 40

Shaymin (Sky)0.91
Kartana0.92
Zarude0.95
Rillaboom0.96
Meowscarada1.05
Chesnaught1.08

A mixed local group

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

2 trainers at level 40

Torterra1.12
Tangrowth1.12
Tapu Bulu1.17
Xurkitree1.20
Celebi1.20
Gogoat1.21

The party these numbers assume

1. Shaymin (Sky)

Magical Leaf + Grass Knot

2. Kartana

Razor Leaf + Leaf Blade

3. Zarude

Vine Whip + Power Whip

4. Rillaboom

Razor Leaf + Frenzy Plant

5. Meowscarada

Leafage + Frenzy Plant

6. Chesnaught

Vine Whip + Frenzy Plant

See the full ranked counter list for Mega Swampert · 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.