How to make fields required for one type of user but not others? (registration and profile forms)
Required By role


  Field required by role is a module that improves core "required"
  functionality.
  
  Similar to CCK Required by role brings extra features such as:
  
  Ready for all entities, including custom entities. Doesn´t need extra
  configuration, just install. Respects previous configuration.
  Configuration per field instance.