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 4 to be safe — 3 if everyone is prepared

At level 40, a party of Mega Swampert's top six counters needs 2.82 trainers (round up: 3), and a mixed lobby of ranks 13-24 needs 3.46 (round up: 4). The raid timer is 300 seconds and one prepared trainer alone would take 12:58. No level in this range makes it soloable with a prepared party.

Mega Swampert · Super Mega

waterground

Weak to

grass

Boss CP: 71,922
Boss HP: 25,000
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	5(4.17)	5(4.55)	6(5.49)	20:56	6.0
Level 25	4(3.62)	4(3.75)	5(4.64)	17:14	6.0
Level 30	3(2.83)	4(3.20)	4(3.87)	14:43	6.0
Level 35	3(2.73)	4(3.07)	4(3.65)	14:08	6.0
Level 40	3(2.62)	3(2.82)	4(3.46)	12:58	6.0
Level 45	3(2.50)	3(2.67)	4(3.32)	12:18	6.0
Level 50	3(2.41)	3(2.54)	4(3.21)	11:43	5.9

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.

3 trainers at level 40

Shaymin (Sky)2.62

A prepared party

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

3 trainers at level 40

Shaymin (Sky)2.62
Zarude2.73
Kartana2.73
Rillaboom2.78
Meowscarada3.02
Roserade3.02

A mixed local group

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

4 trainers at level 40

Tangrowth3.18
Tsareena3.20
Celebi3.35
Xurkitree3.36
Tapu Bulu3.50
Gogoat3.47

The party these numbers assume

1. Shaymin (Sky)

Magical Leaf + Grass Knot

2. Zarude

Vine Whip + Power Whip

3. Kartana

Razor Leaf + Leaf Blade

4. Rillaboom

Razor Leaf + Frenzy Plant

5. Meowscarada

Leafage + Frenzy Plant

6. Roserade

Magical Leaf + Grass Knot

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.