What do you think is the most important factor in deciding characters? Popularity, importance, relevance, or sales?
I think importance is the most important factor in deciding characters. Popularity alone will not get a character in, as shown in Melee, you don't have to appear in the latest game to be considered, and sales is the most overrated as I doubt Sakurai cares about sales that much (He considered Takamaru after Melee despite the original game selling poorly and picked Pit over Takamaru despite the GBA version of Kid Icarus selling worse then The Mysterious Murasame Castle). Importance to a franchise, on the other hand, is undoubtedly important and as Nintendo is about All-Star character, many characters will be picked based off how important they are to their respective series.