What countries' team has participated in the Mediterranean Games successfully since the very first Games were held in Egypt? 
Water polo at the Mediterranean Games: Water polo has been played consistently at the Mediterranean Games since the year 1951. Water polo at the Mediterranean Games:  The Serbia men's national water polo team is the most successful team. 1951 Mediterranean Games: The first Mediterranean Games were held in Alexandria, Egypt, where 734 athletes (all men) from 10 countries participated.
Serbia