I feel like the minimum would be three actually.
Pilot, Mechanic, and chef/cook.
Think of emergencies, before liko and roy came along.
The Pilot and Mechanic would both be busy so you still need a third person to handle the pokemon and such.
But overall I dont see any problem with the number of characters we do have, makes things more lively aboard the ship. Different people to talk to rather than the same 2 or 3 every time.
