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 Altaria's top six counters needs 1.16 trainers (round up: 2), and a mixed lobby of ranks 13-24 needs 1.65 (round up: 2). The raid timer is 300 seconds and one prepared trainer alone would take 5:24. No level in this range makes it soloable with a prepared party. A duo works from level 20.

Mega Altaria · Mega

dragonfairy

Weak to

poisonsteelicefairy

Boss CP: 34,320
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 Altaria 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(1.46)	2(1.70)	3(2.56)	7:53	6.0
Level 25	2(1.20)	2(1.42)	3(2.06)	6:36	5.9
Level 30	2(1.13)	2(1.30)	2(1.81)	6:03	5.9
Level 35	2(1.03)	2(1.22)	2(1.72)	5:40	5.8
Level 40	1(0.99)	2(1.16)	2(1.65)	5:24	5.7
Level 45	1(0.96)	2(1.12)	2(1.59)	5:13	5.6
Level 50	1(0.90)	2(1.08)	2(1.53)	5:02	5.5

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

Zacian (Crowned Sword)0.99

A prepared party

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

2 trainers at level 40

Zacian (Crowned Sword)0.99
Zamazenta (Crowned Shield)1.01
Necrozma (Dusk Mane)1.01
Kyurem (White)1.20
Eternatus1.38
Kyurem (Black)1.39

A mixed local group

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

2 trainers at level 40

Kyurem1.56
Naganadel1.59
Tapu Lele1.61
Enamorus (Incarnate)1.60
Tapu Koko1.62
Lucario1.65

The party these numbers assume

1. Zacian (Crowned Sword)

Metal Claw + Behemoth Blade

2. Zamazenta (Crowned Shield)

Metal Claw + Behemoth Bash

3. Necrozma (Dusk Mane)

Metal Claw + Sunsteel Strike

4. Kyurem (White)

Ice Fang + Ice Burn

5. Eternatus

Poison Jab + Sludge Bomb

6. Kyurem (Black)

Shadow Claw + Freeze Shock

See the full ranked counter list for Mega Altaria · 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.