1: True, but relevance also was important too. I didn't say it was only relevance. I said mostly(which means a big role in it). But fair, it's more the opposite of what I said. My bad.
2: I honestly forgot that was her specific gimmick. Thanks for the correction.
Moveset potential is a more important factor at times(clones aside), but they still need to fit criteria beyond that anyway. Just having potential alone won't work. There has to be more to it than that. Like how to make it interesting, would people recognize the character(in most cases), does it fit something you're already looking for? You'll notice many unique characters not there because they lacked the timing. Games need to be heavily in development and nearly out or were recently out around the time Smash is being created to easily fit the timing window. That doesn't entirely apply to each character, but you gotta remember that not everyone was chosen because of relevance. In some cases, they were chosen for who they are retro-wise as an option. Little Mac is based heavily on his older games since that's where the appeal is. He's not a literal retro character(since his last appearance way on the previous console), however, he was based upon his more retro options and his far older appearances instead. Pac-Man is the same way. He's definitely relevant due to his character overall getting new and active games/works, but he was based upon his retro design specifically. On the other hand, MegaMan didn't have straight-out relevance going for him due to Capcom. However, being iconic, he fit the 3rd party criteria, and was based upon a very memorable version of him, namely, the retro design. Not that he was lacking in games overall over the years, but nothing being worked on/released while Smash 4 was being developed.
That said, I think maybe there's a misunderstanding on how he works with relevance. It means that a character has a new entry that's coming out, or being worked on, during the time Smash is currently being developed. Sometimes it needs to be fairly early on during development(since the roster is often decided somewhat early on), although some clear exceptions exist besides DLC. Namely the clones.
The other thing to remember is that, and it bears repeating; Relevance means this character is currently active. It does not mean "must base them on this appearance". Rosalina isn't directly based upon a specific appearance for her gimmick. It's more an idea based upon the thought of what she could do, including the fact she can work with Lumas. The floatiness and such is more the idea of her being in space and seemingly able to work well with gravity(although to be fair, is this outright mentioned in any game? Cause I haven't played some of them. I know that was part of Rosalina's gimmick, her gravity control, along with being a puppet character archtype).
@PushDustIn Could you link the articles that explain how Relevance is used? I'm not remembering everything or every example well enough to explain. >.<