Here is a guide that shows what they promote to and at what level.

Swashbucklers get Sarah Steele, which promotes to mouse swashbuckler at level 16, and corsair at 37. She starts as a mouse fencer.

s comp Louis le Bisque promotes to Crab Gunner at level 15 and Crab Cannoneer at 38. He starts as a harpooner.

s get Mormo, who promotes to a water mole spirit caller at 15 and obeah at 38. Starts as a witchdoctor.

s get Barnabus, who promotes to a sloth buccaneer at 16, and a sloth warrior at 37. starts as a guardsman.

Privateers get Emmet, who promotes to Leiutenant at 16, and commander at 37. starts as ensign.

Hoped this helped! because you read this, here is a bonus section.

Bonnie anne: Fox musketeer lv 1-7, sharpshooter 7-31, sniper 31-.
Ratbeard: Rat officer(should really be rat pirate) lvl 1- you're lv 10, commander you lv 10-him lv28, captain 28-.