They tend to choose a few proteins and vegetables as focal points each time. I think monkfish was one of the proteins this time.
The Scandinavian countries have been dominating this competition lately, but they pile a lot of resources into it from both corporate and government sponsorships. The competitors are chosen well in advance and given up to a half-year off from their jobs, with plenty of resources for practicing, including a practice kitchen that matches the one that they will use in Lyon.