Is there a standard medical fitness certificate format for applicants to European universities?
I suspect that the right people to ask here are the staff at your local embassy. Certificates of good health, particularly in relation to European institutions, are more likely related to immigration requirements than university requirements. That will mean the embassy will be your best source of information about format. (In fact, there may only be specific doctors authorized to produce such certificates, and you may need to schedule an appointment with one of them, rather than obtain one from your personal primary care physician.)