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 — 5 if everyone is prepared

At level 40, a party of Tapu Fini's top six counters needs 4.52 trainers (round up: 5), and a mixed lobby of ranks 13-24 needs 5.36 (round up: 6). The raid timer is 300 seconds and one prepared trainer alone would take 20:47. No level in this range makes it soloable with a prepared party.

Tapu Fini · Elite

waterfairy

Weak to

poisongrasselectric

Boss CP: 47,317
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 Tapu Fini 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	8(7.59)	8(7.72)	9(8.36)	35:30	6.0
Level 25	6(5.79)	7(6.28)	7(6.81)	28:54	6.0
Level 30	6(5.02)	6(5.25)	6(5.98)	24:11	6.0
Level 35	5(4.76)	5(4.94)	6(5.62)	22:44	6.0
Level 40	5(4.36)	5(4.52)	6(5.36)	20:47	6.0
Level 45	5(4.23)	5(4.31)	6(5.18)	19:50	6.0
Level 50	5(4.16)	5(4.13)	5(4.94)	19:01	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.

5 trainers at level 40

Zeraora4.36

A prepared party

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

5 trainers at level 40

Zeraora4.36
Eternatus4.45
Xurkitree4.53
Kartana4.52
Regieleki4.58
Thundurus (Therian)4.66

A mixed local group

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

6 trainers at level 40

Nihilego5.08
Necrozma (Dusk Mane)5.13
Zamazenta (Crowned Shield)5.24
Necrozma (Dawn Wings)5.24
Roserade5.29
Zacian (Crowned Sword)5.36

The party these numbers assume

1. Zeraora

Spark + Plasma Fists

2. Eternatus

Poison Jab + Sludge Bomb

3. Xurkitree

Thunder Shock + Discharge

4. Kartana

Razor Leaf + Leaf Blade

5. Regieleki

Thunder Shock + Thunder Cage

6. Thundurus (Therian)

Volt Switch + Wildbolt Storm

See the full ranked counter list for Tapu Fini · 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.