This is "Rate My Team," not "Give Me a Team." Figure something out first before you post here.
Anyways, the problem with making a Fire Mono Team is that there aren't that many fire types out there. And many of those fire-types have a similar and small movepool. Almost all fire types have a fire move (duh), a ground move like Earthquake and/or a rock move like Rock Slide, and Hidden Power in their moveset since that's usually the best they can get. Also, most if not all fire types are meant, or at least are most effective as, sweepers. That leaves you without any support Pokemon to support the rest of your team. The only exception that I can think of is Ninetales but Ninetales operates best as, for the lack of a better term, an annoyer.
Basically, most fire pokemon are the same and don't have much variety in their movesets or strategy. As a result, the right Pokemon can easily defeat such a team single handedly or with minimal support. A water or ground type would easily destroy a fire mono team.