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 Zekrom's top six counters needs 1.94 trainers (round up: 2), and a mixed lobby of ranks 13-24 needs 2.54 (round up: 3). The raid timer is 300 seconds and one prepared trainer alone would take 8:56. No level in this range makes it soloable with a prepared party. A duo works from level 40.

Zekrom · Tier 5

dragonelectric

Weak to

groundicedragonfairy

Boss CP: 53,394
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 Zekrom 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(2.80)	4(3.29)	4(3.95)	15:08	6.0
Level 25	3(2.03)	3(2.69)	4(3.38)	12:23	6.0
Level 30	2(1.77)	3(2.24)	3(2.86)	10:19	6.0
Level 35	2(1.72)	3(2.03)	3(2.65)	9:22	6.0
Level 40	2(1.64)	2(1.94)	3(2.54)	8:56	6.0
Level 45	2(1.58)	2(1.88)	3(2.45)	8:39	6.0
Level 50	2(1.53)	2(1.82)	3(2.35)	8:24	6.0

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

Eternatus1.64

A prepared party

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

2 trainers at level 40

Eternatus1.64
Kyurem (Black)1.79
Kyurem (White)1.90
Baxcalibur2.10
Dialga (Origin)2.10
Palkia (Origin)2.12

A mixed local group

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

3 trainers at level 40

Reshiram2.44
Groudon2.43
Dialga2.47
Haxorus2.49
Salamence2.52
Kyurem2.51

The party these numbers assume

1. Eternatus

Dragon Tail + Dynamax Cannon

2. Kyurem (Black)

Dragon Tail + Freeze Shock

3. Kyurem (White)

Dragon Breath + Ice Burn

4. Baxcalibur

Ice Fang + Glaive Rush

5. Dialga (Origin)

Dragon Breath + Roar of Time

6. Palkia (Origin)

Dragon Tail + Spacial Rend

See the full ranked counter list for Zekrom · 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.