Thinking of characters as "reps", be it for franchises or companies, seems like it's a poor way to conceive of characters.
Sakurai will occasionally reference thinking of a franchise to include first and then filing in the character later (



) or leaving a spot open for a new character from a revolving door franchise that is later filled in (




) but these seem to be the exception. More often than not, Sakurai will instead note a character's intrinsic qualities when qualifying why they were added to Smash.
Every game seems to draw less and less of a distinction between the first and third parties. IMO, corporate ownership only feels relevant to the extent that licensing costs and a company's general cooperativeness when adding content.
I think a lot of this thinking is primarily inertia from information about Sakurai's thought process was moreso behind a language barrier and a desire for certain series that have been neglected to get characters for their own sake.