If she was included, my guess is that she would probably be a Peach Clone. At least for some of her moves and character hitboxes.
Whilst I wouldn't be entirely surprised by a loose, "Luigified" semi-clone approach possibly being taken with Daisy, I'd be interested to hear which of Peach's moves you feel would suit Daisy to the point that she'd be a regular clone as your post suggests, if you're willing to share.
Theres just not alot of games that she can take moves from.
That's ok. Even if we're not considering Daisy's appearances in the many spin-offs in which she's appeared (in which case we have Super Mario Land and Super Mario Run to draw from), a lot of stuff gets made up for Smash anyway, either based on characters' personalities, or fabricated outright - for example, there's no game where Donkey Kong spins his entire body in order to use his arms to fly like a helicopter, Fox and Captain Falcon's moves were all created specifically for Smash, the dog from Duck Hunt didn't cross over with multiple other NES Zapper games, and Ganondorf isn't Captain Falcon in disguise in order to go undercover in the Zelda games.
I don't recall Zelda's Sheik disguise having much to draw from in her lone NPC appearance in the Zelda series, either, come to think of it.
Considering that there's also Mr. Game & Watch, who's not a real character from a Game & Watch game at all, but instead a made-for-Smash amalgamation (he has the appearance of a generic NPC from Fire, instead of the personality-filled look that most Game & Watch characters had, with random moves from several other Game & Watch titles grafted onto him), I don't think that they'd have any difficulty combining both Daisy's personality-traits and numerous game appearances to create a fitting moveset for her if she were added to Smash.
Sure, they could make Daisy a straight re-skin of Peach, but not only would that be a missed opportunity since their biggest similarity in this day and age is ultimately that they're both princesses who wear dresses, the fact that they didn't do so in Smash 3DS/Wii U, where they did this sort of thing a fair bit to pad out the roster, suggests that they may not be inclined to take that route with her.