The thing is though is that nobody really doubts that Sakurai can make Daisy work in terms of "simply getting her into the game and making her functional", or any character, for that matter.
The point I'm trying to make is that what's the point of putting Daisy into the game when A) her character hasn't been defined with many particularly interesting traits from a personality or ability stand point in the very series she comes from, and B) what little she has could only be aesthetically distinct, and only to a small degree at that?
Every other character that got into Smash had some sort of very defined basis for why they got in. With Rosalina for example, having Luma as a helper made sense because of A) her deep relationship with Lumas which is part of what makes her interesting even as just a character, and B) because it referenced the Co-Star Luma mechanic from Galaxy 2 (also Lumas are generally helpful creatures and help many characters throughout the game - such as building a Starshroom for Captain Toad and the Toad Brigade in both games). Rosalina's moveset also incorporates stuff like her control over gravity, and other things if we go into the nitty gritty of it all. And all of these elaborate powers of hers link back to her graceful, cosmic goddess role, which again, is an interesting part of her character from just a lore standpoint. All of these elements together form a character (or two) that is both UNIQUE AS A FIGHTER COMPARED TO THE REST OF THE CAST and A DISTINCT, FLESHED OUT PERSONALITY THAT IS LOVABLE AS A CHARACTER.
Daisy doesn't really have anything like that in the Mario games as it stands, which you can't really deny no matter how attached to the character you are. She has no fleshed out backstory, she has no storied history of adventures, she doesn't appear in a main series game (SML isn't a main series game - it's a spin-off made by Nintendo R&D1, not a main series game made by Nintendo EAD), she hasn't got a vast and expansive move pool or at least an attribute to derive from, her design isn't incredibly standout and distinct, and her personality is just "energetic and girly" and nothing else, which is very generic.
Daisy can be a Peach alt/clone as it stands that mixes her up by giving her those few distinct elements she has and fusing them with what Peach already has (because Daisy is undeniably derived from Peach as is). What she has right now doesn't deem her worthy of a full moveset though.
Daisy WOULD be worthy of a fully original moveset if Nintendo put her in an RPG or something and actually re-did her design (at least make her tan and change her dress up to be less like Peach's, like how Rosalina is pale and has her own distinct outfit), and gave her weapons or powers that are specific to her (I think a whip made out of flowers called the "Daisy Chain" would be amazing). While Sakurai could do those things by himself, Daisy would get a negative reception if he did because she would literally be "forced" into the game. It would be better if the Mario franchise itself had a game that has Daisy in it and gives her a big role and gives her a weapon or powers to call her own, with a more distinct design. And THEN they put her into Smash.
