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 6 to be safe — 4 if everyone is prepared

At level 40, a party of Dialga's top six counters needs 3.94 trainers (round up: 4), and a mixed lobby of ranks 13-24 needs 5.28 (round up: 6). The raid timer is 300 seconds and one prepared trainer alone would take 18:08. No level in this range makes it soloable with a prepared party.

Dialga · Elite

steeldragon

Weak to

fightingground

Boss CP: 61,654
Boss HP: 20,000
Raid timer: 300s
Party used: 6

Trainers needed, by attacker level

Scroll sideways for the mixed-lobby column.

Trainers needed to beat Dialga 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	6(5.70)	7(6.69)	9(8.19)	30:47	6.0
Level 25	6(5.29)	6(5.73)	7(6.73)	26:22	6.0
Level 30	5(4.21)	5(4.89)	6(5.96)	22:31	6.0
Level 35	4(3.66)	5(4.27)	6(5.60)	19:40	6.0
Level 40	4(3.19)	4(3.94)	6(5.28)	18:08	6.0
Level 45	4(3.05)	4(3.70)	5(4.84)	17:02	6.0
Level 50	3(2.99)	4(3.60)	5(4.53)	16:34	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.

4 trainers at level 40

Keldeo3.19

A prepared party

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

4 trainers at level 40

Keldeo3.19
Lucario3.67
Terrakion3.81
Kartana4.23
Groudon4.30
Urshifu (Rapid Strike)4.43

A mixed local group

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

6 trainers at level 40

Landorus (Therian)4.74
Marshadow4.77
Conkeldurr4.96
Gallade5.00
Rhyperior5.21
Mewtwo5.11

The party these numbers assume

1. Keldeo

Low Kick + Secret Sword

2. Lucario

Force Palm + Aura Sphere

3. Terrakion

Double Kick + Sacred Sword

4. Kartana

Fury Cutter + Sacred Sword

5. Groudon

Mud Shot + Precipice Blades

6. Urshifu (Rapid Strike)

Counter + Dynamic Punch

See the full ranked counter list for Dialga · 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.