My fictional novel includes characters who play for the Boston Red Sox. Obviously, I am using fictional characters and a made up storyline, but am I allowed to use the name of the team or is that copyright infringement?
I actually did some research online and it turns out you CAN use professional sports teams. They are public use. It does not matter that they are trademarked names. The only restrictions are trademark infringement (you are profiting by selling a similar product with THEIR trademark) trademark dilution (i.e. using it in a generic fashion -- coke instead of Coke or saying a character xeroxed a paper instead of Xerox) or libel (using their trademark such a way as to cast a negative image and makes them lose customers)
Does it have to be a pro team? When you harness your story to a professional sports team—or any legitimate organization for that matter—you automatically invoke collective public memory in the form of lore, sentiments, perceptions, and history. However if your character development can still occur in the context of minor leagues, you'll avoid all of this.
For example, I'd be shocked if anyone could recall players for the 1994-95 Houston Aeros off the top of their head. However, as a hockey fan, even though I'm not a Dallas Stars fan, I know off the top of my head that the 94/95 Stars included players like Mike Modano and Derian Hatcher. So a story about that team in the middle 90's would be off-putting if those characters where given zero treatment and entirely overlooked.
So with the above in mind, my suggestion would be that you give your story some kind of anchor in reality. Research and recognize a few nuggets that naturally link your story to the collective consciousness, and I think you'll have a stronger narrative. Fictional characters could be called up for some reason, or they could already be a minor pros elsewhere in the BoSox farm system watching from a distance and hanging on the details. But I think outright eliminating legitimate, historical connections and characters that our public consciousness expects to be present in a given context would be a mistake. In fact, for me it's almost insulting somehow.