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 Mega Mewtwo Y's top six counters needs 1.54 trainers (round up: 2), and a mixed lobby of ranks 13-24 needs 1.85 (round up: 2). The raid timer is 300 seconds and one prepared trainer alone would take 7:09. No level in this range makes it soloable with a prepared party. A duo works from level 30.

Mega Mewtwo Y · Mega

psychic

Weak to

bugghostdark

Boss CP: 62,640
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 Mewtwo Y 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(1.88)	3(2.40)	4(3.03)	11:09	6.0
Level 25	2(1.63)	3(2.01)	3(2.49)	9:21	6.0
Level 30	2(1.39)	2(1.73)	3(2.10)	8:02	6.0
Level 35	2(1.31)	2(1.63)	2(1.96)	7:34	6.0
Level 40	2(1.20)	2(1.54)	2(1.85)	7:09	6.0
Level 45	2(1.17)	2(1.50)	2(1.77)	6:59	6.0
Level 50	2(1.12)	2(1.45)	2(1.71)	6:44	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.

2 trainers at level 40

Necrozma (Dawn Wings)1.20

A prepared party

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

2 trainers at level 40

Necrozma (Dawn Wings)1.20
Lunala1.55
Darkrai1.57
Hydreigon1.60
Tyranitar1.62
Eternatus1.68

A mixed local group

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

2 trainers at level 40

Chandelure1.81
Kingambit1.76
Hoopa1.79
Volcarona1.84
Incineroar1.82
Hoopa (Unbound)1.82

The party these numbers assume

1. Necrozma (Dawn Wings)

Shadow Claw + Moongeist Beam

2. Lunala

Shadow Claw + Shadow Ball

3. Darkrai

Snarl + Foul Play

4. Hydreigon

Bite + Brutal Swing

5. Tyranitar

Bite + Brutal Swing

6. Eternatus

Dragon Tail + Dynamax Cannon

See the full ranked counter list for Mega Mewtwo Y · 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.