Why Jerry appears instead of Calypso
The Jerry reference describes him substituting when Call: Calypso is used before you speak to Calypso after completing Chapter 5. Return to her at Pirate Camp to follow up on that story state.
What Jerry does
His loop is Flower → SP Wave → Flower?. The first can damage and Confuse an enemy; SP Wave restores 2 SP to players; Flower? trips and does nothing. This is a summon behavior, not an enemy pattern you must defeat.
If you meant Terry’s battle
Tutorial Terry has a separate scripted encounter and the A Price to Pay badge. Use his page for the hostile dialogue option and why normal damage cannot win it.