I'm writing a fanfic where an anonymous pirate user known only as "Captain" of the Hypno-Hypno No Mi uses his fruit on Nami and Robin to make them desert the Straw Hats and join the Spiral Pirates or a crew composed of the "captain" and his wives and the problem I have about the roles of the crew at the moment the roles I have in mind are:
Navigator: Nami
Archaeologist: Robin
Doctor: Tristan
The one I want you to help me with is to give ideas so that characters could occupy the following roles in the crew:
-Swordswoman
-Cook
-Musician
-Shooter
-Carpenter
-Helmsman

You should flesh out your captain more first I think, but I trust you've given the character more thought than what you've said here.

Since you're doing hypnosis, there's no reason to have a character stick exactly with the role that they're already good at, there can be a lot of fun in making a character do something against their nature. Consider the following.
-Monet if made sweet and doting she could make a good musician
-Vegapunk York could make an ironic cook if you suppress her vices. She could also be a carpenter, since she is a good engineer.
-Robin doesn't have to be an archaeologist, her power would also make her a very capable helmswoman.

There are also some easier picks. Charlotte Pudding would make a good cook, as would most girls from whole cake island. Most characters from Wano could make good swordswomen. Carrot is a good flex pick, since I could see her doing most jobs. Kalifa could be a carpenter using her soap power to maintain the ship, or a shooter. Uta is a Musician, though that's playing it so straight I find it boring.

And thinking a lot about the Captain, he is basically a hedonist who lived his childhood being poor and who dreams of living as a pirate for a few years, saving up enough money to live well for the rest of his life and spend the rest of his days living happily the rest of his days after turning his female crew into his wives.



If I'm honest, I'm also considering doing something more kinky with Robin, like turning her into a jester or the crew's pet after lowering her IQ and erasing her memory as part of a contract with the world government.

Not a fan of bad ends like that, but I do love jesters.