Impa's requests have gotten higher, but it's split among different versions of her, and not the concept even as a composite of multiple ones is that popular. It's just specific ones that jump out to people(SS, HW, and AOC are all separately popular characters too).
She doesn't really eclipse Skull Kid and Midna by any means, since it's 3 fairly popular renditions of Impa that have gained traction throughout the years. They still ultimately are more popular than her.
I'd like a Ganondorf stance character or just another character altogether for a different moveset. Either works. He's very fun to use, since he's a great physical powerhouse(just like in canon) while using a fair bit of magic in more than one way. Channeling his magic into straight power isn't even odd anyway. This is an actual thing in fiction. That, and only Dark Dive among his specials has no real basis in animations or even a loose interpretation of something he does, making it oddly the least canonical move. He does Kick and Punch in canon(and his Forward Air is directly taken from official artwork). Only projectile I feel fits best is the Lightning Ball, if only because it's easy to be truly faithful to it(DMV is literally not just a Boss Move, so harder to transfer over, but the basis of the move is how easy it needs to be able to be reflected. It's named after the whole point, being specific "Volleyball"(despite the tennis jokes, it's more about hitting it back with a weapon, not just returning it alone) in multiple languages too to drive home the point(officially the names are Vicious Volleyball in French, Hellish Volleyball in German, and Infernal Volleyball in Spanish). It's actually not even that odd of a term, when you realize he outright flings it similar to a Volleyball Serve.
Also, it's worth keeping in mind DMV is never used officially outside of Phantom Hourglass as a name. So who knows what they used to call it in development or in the specific files. This also is worth noting that it was never named anyway, and thus, is kind of hard to define as a move to give to Ganondorf at any point till Phantom Hourglass released, which is as early as 4. That's already 3 games in. All we know is that as a projectile, it needed to be reflected to be faithful. And even then, it was always just a way to damage the boss, with other projectiles usually used to make sure it wasn't a one-note and easy battle. That, and said Lightning Ball attack is worth noting that it splitting into projectiles happens more than once(it's the "Blue Balls" move Aganahim uses, and the multiple projectile move that OOT Ganondorf and WW Phantom Ganon use. Also, for a twist of irony, even Link has that ability in HW, while in Great Fairy form(though keep in mind it's basically a cutscene before the Great Fairy herself lanuches a full-powered projectile in general. Link and the Great Fairy directly do DMV against each other during the cutscene, so even in the rare instance a player character can use it, it's not something you can throw into a fighting game logically. It's still super different from how it can function. It could work as a Final Smash, though, in that particular style).
Anyway, I do think the multi projectile(which is basically "Lightning Ball" originally. Though TP is the first to use a different move that changes up its function) would do wonders for him. It's hard to actually reflect by design(though if you want to be faithful, any reflector that is a Smash attack would need to be fully charged, and a normal Reflector/Deflector should work functionally as is since it'd be a really poor balance if it didn't. Knocking out the current Reflector shield so it can't be held down would be a potential balancing factor though). Or you could use the slightly different TP version which isn't multi-layered, and could be a normal reflectable attack, deal good stunning damage, and not be awkward in function, but still very faithful in practice. That said, DMV wouldn't be complete if it couldn't be reflected by a few silly things(Bug Nets, Bottles, etc), so even if what reflects it is limited, those kind of things are what made it such an interesting boss ability. That it had hidden ways to reflect it back. That gives it a lot of life. To say the least, there's more than once nice direction to go in for a projectile.
...He does need a reflector the most, though. Oof.