...But what's the point of that?
If a character has a unique moveset, and can do something nobody else in the roster could give, why does it matter what games they come from?
As long as a franchise doesn't make up the most of the roster, who cares where they come from? I mean, yes, 20% of the SSB4 characters come from the Mario games and lore, but who cares? Mario is Nintendo, the huge flagship franchise, of course you're going to see a sh*t-ton of characters who come from Mario games, they're iconic and recognizable. Even then, you see Yoshi, DK and Wario making a name for themselves.
That's a problem I see a lot, this whole "representation and relevancy" thing. They do have a part in selection, we know that, but their role is so miniscule in the final part of it. Sakurai, from what we know, looks at these characters and looks into seeing what they could do as a fighter based on build, abilities, their origin game / franchise, etc. Characters aren't finalized because "oh, we need them because they're important to their franchise / fill a certain niche". That doesn't mean anything if they can't do jack.
That's why I despise the idea of "slots" and "representation". Characters are determined, in the end, by playstyle. Not to be rude, but the ideas I saw during speculation for Rosalina and Bowser Jr. were rather uninspired. There wasn't anything different to them, it felt like just giving them moves because "they can do that in that one game." Now, we have a puppet master Rosalina, and a mech-wielding Bowser Junior, something I've never seen suggested for them, but still does the characters justice and makes them different instead of just being Space Peach or Baby Bowser.
I kind of went off on a tangent here, but still. If they were to add back in

/

, they're not going to just say "oh, they're both Pokemon, we already did Mewtwo, so it's a waste of our time." People want veterans back. What I'm saying is that it's just the noise for these two isn't nearly as loud as, say,

/

.