Produce clear and coherent writing in which the development, organization, and style are appropriate to task, purpose, and audience. (Grade-specific expectations for writing types are defined in standards 1-3 above.)

This one shouldn't need much further explaining, especially since there are three other Common Core Standards describing exactly how to fulfill this standard. Just make sure that students are writing in a way that makes sense for the form of writing they're doing. Of course, if a student wants to write a persuasive essay in short story form, then by all means let him or her try it.