I guess the only one where it doesn't really fit is Daisy and it's widely accepted that she should be more different.
Outside of the Toad Guard, this actually is a more retroactive thing.
When Ultimate's roster was decided, Daisy's ONLY platformer outing was her debut in Super Mario Land....as the stand in for Peach as the damsel in distress.
Super Mario Run hadn't been out yet, let alone with Daisy's inclusion to actively give her unique attributes such having no float but an extra jump. And if Wonder was out before she was added in Smash as well, I'd definitely be arguing in favor of her taking from that while Peach keeps her style from SMB2 since that alone would make them distinct. But alas, what's done is done now. But maybe her float could be swapped out for an extra midair jump next Smash.
And in a
majority of the spin-offs, Daisy doesn't actually do much that's different from Peach. Sure, she has more spunk in her animations, but there's no reason to assume she wouldn't have the same attributes and abilities in Smash when the times she has something different can be counted on one hand.
Except again Toad Guard for example which doesn't fit her at all since she's not part of the Mushroom Kingdom. But that could easily be worked around with a denizen of Sarasaland like a Pompom Flower that spits pollen like Toad's spores.
Daisy actually works fine for an Echo, especially in the timeframe where her only mainline outing was as a replacement for Peach.
The main problem is that she's near 1:1 to the point she's
pointless as her own character, the only gameplay differences being slight hurtbox differences when standing still or running, which....doesn't mean much in retrospect with how a Peach/Daisy player is going to use the character.
Like even giving her the Flower Bomber custom Side Special for Peach in Smash For would've made it better. Or even keeping the Turnip difference that was patched to be exactly like Peach in an update.