Think of anything that can be cooked on whatever gear you have. Many times desserts can be made in advance and brought to the contest already prepared. Usually there is a theme, so I would check what the contest organizer has listed as the rules for the open category. You also want to check the garnish and presentation rules too.
Desserts, especially cheesecakes are popular, lamb, steak, fish, seafood, lobster, stews, soups, chili, items cooked in dutch ovens, pork crown roasts, mac-n-cheese, burgers.