Where to unlock the fight
After Chapter 4, go south of Vermillion Village to The Dunes Spot. Finn has 100 base HP and Mobile. The rewards are Aggressor and Converging Timelines. He does not block the main chapter route.
Two baseball shots, two rhythms
Quick Baseball Shot tosses and immediately strikes the ball. Stalled Baseball Shot catches it on the bat and lifts it twice before the real hit. Both deal 20 base damage and can Confuse; guard the ball’s arrival, not the initial toss.
Charge Power → Bat Smackdown
The bat toss and crouched pose mark Charge Power. The follow-up hits twice with the bat, then finishes with a delayed kick, for 30 total base damage. If you avoid it with Ghost Potion, keep 1 SP and allow for Exhausted afterward.
Mechanics references: Ghost Potion
Flex changes the next stretch of the fight
The normal order is Bat Combo → quick shot → stalled shot → Flex → Call for Help → Charge Power, with the charged attack overriding the next normal move. Flex heals his team by 2 and gives Fine and Fast. Call for Help fills up to three open slots with Shotgun Blokes or Megaphone Men.
Choose a summon response from the field
If extra enemies are forcing recovery every action, remove one before returning to Finn. If Finn is almost defeated, finishing him can be more efficient than restarting on three fresh targets. Reassess after Flex; a fixed damage rotation ignores its speed buff and the new enemies.