User blog comment:GuyWithTheCoolName/Smash 4 Roster Prediction/@comment-4115159-20140714003818/@comment-25161957-20140714105002

The "five character rule" is not a rule, it is an interpretation of a non-existant rule that people try to follow. It makes sense though, as having six characters in a franchise and only five in some other ones would be an example of poor roster reviewing.