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 Charizard Y's top six counters needs 1.00 trainers (round up: 2), and a mixed lobby of ranks 13-24 needs 1.32 (round up: 2). The raid timer is 300 seconds and one prepared trainer alone would take 4:40. A prepared solo becomes possible at level 45. A duo works from level 20.

Mega Charizard Y · Mega

fireflying

Weak to

rockwaterelectric

Boss CP: 47,739
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 Charizard 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(1.48)	2(1.51)	3(2.03)	7:02	6.0
Level 25	2(1.29)	2(1.28)	2(1.73)	5:58	6.0
Level 30	2(1.10)	2(1.12)	2(1.50)	5:13	6.0
Level 35	2(1.03)	2(1.05)	2(1.39)	4:54	6.0
Level 40	1(0.94)	2(1.00)	2(1.32)	4:40	6.0
Level 45	1(0.90)	1(0.96)	2(1.26)	4:28	6.0
Level 50	1(0.87)	1(0.93)	2(1.21)	4:20	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.

1 trainer at level 40

Rampardos0.94

A prepared party

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

2 trainers at level 40

Rampardos0.94
Glimmora0.96
Rhyperior1.00
Tyrantrum1.01
Terrakion1.04
Gigalith1.06

A mixed local group

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

2 trainers at level 40

Lycanroc (Dusk)1.24
Lycanroc (Midday)1.24
Stakataka1.27
Lycanroc (Midnight)1.27
Alolan Golem1.30
Golem1.31

The party these numbers assume

1. Rampardos

Smack Down + Rock Slide

2. Glimmora

Rock Throw + Meteor Beam

3. Rhyperior

Smack Down + Rock Wrecker

4. Tyrantrum

Rock Throw + Meteor Beam

5. Terrakion

Smack Down + Rock Slide

6. Gigalith

Lock-On + Meteor Beam

See the full ranked counter list for Mega Charizard 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.