Can I make a calendar using purchased sports team logos, or do I need to get legal permission?
You need legal permission to make a calendar using purchased sports team logos. You can be sued by the sports team if you make the calendars and sell them because the sports teams have patents rights to the logos.
If you're going to sell it you need permission from each team. You can be heavily fined if you are using logos without permission. If you are using it for personal use then you should be fine.