Sooner or latter every main character gets sidekicks/proteges/or simply some new inspired character. For you personally how many is best for a family size? I think most would agree Batman has just too many at this point while someone like Aquaman could use one or two more.

For me I think once you start getting over 3 active sidekicks things start getting sloppy and fans start getting upset becuase the one the like is not getting used while one they don't is.