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 5 to be safe — 4 if everyone is prepared

At level 40, a party of Mega Zeraora's top six counters needs 3.62 trainers (round up: 4), and a mixed lobby of ranks 13-24 needs 4.53 (round up: 5). The raid timer is 300 seconds and one prepared trainer alone would take 16:39. No level in this range makes it soloable with a prepared party.

Mega Zeraora · Super Mega

electric

Weak to

ground

Boss CP: 83,018
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 Zeraora 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(4.79)	6(5.12)	7(6.68)	23:35	6.0
Level 25	4(3.97)	5(4.45)	6(5.68)	20:28	5.9
Level 30	4(3.64)	4(3.96)	6(5.10)	18:13	5.7
Level 35	4(3.47)	4(3.76)	5(4.73)	17:18	5.6
Level 40	4(3.33)	4(3.62)	5(4.53)	16:39	5.6
Level 45	4(3.03)	4(3.46)	5(4.38)	15:54	5.4
Level 50	4(3.01)	4(3.39)	5(4.22)	15:36	5.3

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.

4 trainers at level 40

Landorus (Therian)3.33

A prepared party

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

4 trainers at level 40

Landorus (Therian)3.33
Groudon3.44
Eternatus3.64
Excadrill3.72
Garchomp3.77
Kyurem (Black)3.81

A mixed local group

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

5 trainers at level 40

Golurk4.31
Krookodile4.29
Regigigas4.35
Mudsdale4.47
Donphan4.50
Golem4.55

The party these numbers assume

1. Landorus (Therian)

Mud Shot + Sandsear Storm

2. Groudon

Mud Shot + Precipice Blades

3. Eternatus

Poison Jab + Dynamax Cannon

4. Excadrill

Mud-Slap + Scorching Sands

5. Garchomp

Mud Shot + Earth Power

6. Kyurem (Black)

Dragon Tail + Freeze Shock

See the full ranked counter list for Mega Zeraora · 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.