On Clones, I have two definitions
Semi-Clones- Character that take most of their aspect from a character, but bring in their own twist with the addition of new moves, different stats, and a unique niche in the meta-game
Clones (Echo Fighters)- Character that takes almost all of their aspects from a character, with the only noticable changes being the model swap, and maybe a different property.
The difference is that each of the semi-clones has a unique niche that changes the playstyle of the character differently. Falco is meant to be played differently from Fox. Dr. Mario is meant to be played differently from Mario. Falcon is meant to be played differently from Ganondorf.
A true clone is when the character can easily be interchangable with it's counterpart. There is no different playstyle for either Pit or Dark Pit. They both play the same. Similary, while there might be slightly different concepts, Lucina plays very similarly if not identical to Marth. (the unique property that Lucina brings is that she has no tipper, which basically eliminates the concept that made Marth unique- Spacing. Lucina is basically a Marth without his niche, and Lucina doesn't bring a unique niche to replace it.)
I theorize that Daisy will play pretty much the same as Peach. There might be a difference, but it wouldn't be enough to change the general playstyle of the character.