There are challenges associated with mixing fowl varieties, such as making sure each one eats the right food for their needs. Often different fowl have different nutritional requirements, so sometimes they won't be healthy if they all eat the same food. Will you offer them all layer feed for chickens, feed designed for your other fowl, or something else entirely that is a compromise between the two? It may be hard to find something they can all eat that will keep them all at their best when their care needs are so different.
Ducks, geese, guineas, peafowl, quail, pheasants, turkeys and so on all have their own challenges and individual care requirements. For instance, some illnesses that are mild in chickens can be fatal to turkeys. Chickens need a dry coop, but ducks need lots of access to water. Some game birds need a considerable amount of room when compared to chickens. There are lots of concerns to address. You will have to do careful research to determine what those specific challenges are in order to see if it's possible for you to make safe plans for all your birds, especially if you mean to house them together.