The sky is the limit when it comes to foods for Fat Tuesday. As Wednesday starts Lent (40 days to Easter), traditionally there is a huge meal that is filled with excess! Also because many people fast meats during this time, Fat Tuesday is a great time for meats of all shorts. In light of this, let me give you some suggestions.
First, pancakes with all sorts of sweets are a good starter. This can be good for twenty people, because this is easy to make.
Second, meats can be given as well. I suggest steak strips with some sort of bread. In the past I had fajitas with steak strips and plenty of grilled vegetables. By making these fajitas, you also get a communal aspect.
As for desserts, you can make your own donuts and have an assortment of cakes of all kind. Cheese cakes with fruit is another favorite. Another option is to set up a chocolate fondue with fruits.