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 3 to be safe — 2 if everyone is prepared

At level 40, a party of Xerneas's top six counters needs 1.79 trainers (round up: 2), and a mixed lobby of ranks 13-24 needs 2.50 (round up: 3). The raid timer is 300 seconds and one prepared trainer alone would take 8:15. No level in this range makes it soloable with a prepared party. A duo works from level 30.

Xerneas · Tier 5

fairy

Weak to

poisonsteel

Boss CP: 45,899
Boss HP: 15,000
Raid timer: 300s
Party used: 6

Trainers needed, by attacker level

Scroll sideways for the mixed-lobby column.

Trainers needed to beat Xerneas 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	3(2.08)	3(2.58)	4(3.75)	11:53	6.0
Level 25	2(1.81)	3(2.25)	4(3.16)	10:21	5.9
Level 30	2(1.61)	2(1.96)	3(2.79)	9:02	5.9
Level 35	2(1.54)	2(1.87)	3(2.65)	8:37	5.8
Level 40	2(1.48)	2(1.79)	3(2.50)	8:15	5.7
Level 45	2(1.43)	2(1.73)	3(2.38)	7:59	5.7
Level 50	2(1.36)	2(1.67)	3(2.27)	7:40	5.7

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

Zamazenta (Crowned Shield)1.48

A prepared party

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

2 trainers at level 40

Zamazenta (Crowned Shield)1.48
Zacian (Crowned Sword)1.48
Necrozma (Dusk Mane)1.56
Eternatus2.01
Metagross2.08
Necrozma (Dawn Wings)2.15

A mixed local group

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

3 trainers at level 40

Naganadel2.37
Lucario2.51
Genesect2.46
Genesect (Burn)2.46
Genesect (Chill)2.46
Genesect (Douse)2.46

The party these numbers assume

1. Zamazenta (Crowned Shield)

Metal Claw + Behemoth Bash

2. Zacian (Crowned Sword)

Metal Claw + Behemoth Blade

3. Necrozma (Dusk Mane)

Metal Claw + Sunsteel Strike

4. Eternatus

Poison Jab + Sludge Bomb

5. Metagross

Bullet Punch + Meteor Mash

6. Necrozma (Dawn Wings)

Metal Claw + Moongeist Beam

See the full ranked counter list for Xerneas · 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.