Use logic to mention a new nakama for the straw hat pirates.
All in Luffy´s crew are important or useful
Brook(Musician and Swordsman)
Now use logic for a new nakama.
It would be useful a fishman to help the crew navigating underwater with a serious personality and his dream could be travel around all the seas or maybe a scientist to create or invent cool stuff for the crew better than Usopp´s ones or Franky´s ones and maybe help Chopper with medicines with a crazy personality(crazy scientist) and his dream could be surpass Dr. Vegapunk(his father o,O).
I really doubt that a Shichibukai or someone that is in the prison will join Luffy´s crew for now.
I think the new nakama they will get will be in the Fishman Island.
Describe a new nakama for Luffy´s crew, its personality and dream.
Remember all in Luffy´s crew has a different personality and different dream.