The new Historical Exhibition mode allows you to set up an exhibition game or series between two historical teams. This mode can be accessed from the OOTP main menu. If you want to create a league with historical teams from different years, you can do that, too. It's a bit more complicated. The manual describes the process:
Out of the Park Developments Online Manuals
It may take a bit of trial and error to get the hang of it. But after that, it's easy to do.