As far as I've come to experience Dixie over my years, she's shown to be distinctive enough from Diddy Kong in her playable appearances, something I've found increasingly confusing for this entire community to be ignorant of. Probably it might be due how both Kongs share similar body builds and how there's easy huddling of similar-looking characters to be labeled as clones of others, and how it fits thus to a tee for them to be such in Ultimate as well. It's kind of sad because I rather see everyone pop in with something enough unique to bring into the table.
To showcase why Dixie being an Echo feels so clashing and unappealing concept to me, here's a video of how it could look like in practice, based on Ultimate's general treatment of Echo Fighters:
Compare that to how she moves, and uses her innate abilities in canon:
The thing about Dixie becoming Diddy's echo would mean she'd be moving, acting, and playing
exactly as
Diddy Kong (in-your-face monkey scrapper) - but if you played her in the games she's in, you could see that she's little too elegant and subdued character compared to Diddy Kong, to just pass for borrowing stuff from him (like how
was forced to, yeesh).
Another difference with Dixie and other Echoes (sans Richter) is that she has build quite a legacy for herself, enough to spawn a related expy in DK64 and grown her own character and combat abilities as result. To sweep that all away just to make it easy to add her in would feel big slap in the face for her fans, and probably elicit more false impressions of her being the Daisy to Diddy Kong's existence - and Smash's influence can be at times damaging to certain characters as I've seen (
,
,
)
It'd be even worse with Isabelle apparently being given more preferential treatment, which'd make Ultimate's development and overall claim in being true to characters feel lousy lies at times.
On that end, I personally would find it upsetting that Smash would popularize Dixie being "Girl Diddy" to a point her ponytail, the most iconic trait about her bar none, would just end up a mere aesthetic look to her over time.
On other choices for Diddy as Echoes, they all seem little difficult to envision as Diddy's Echoes in a seamless fashion as I wish them to be, i.e
. DK Jr. might feel most "thrown-in" that'd not offend anybody, but I think I'd prefer Richter to DK Jr-esque additions anyday.
Perhaps Salsa might feel most funnest addition, and pay tribute to his prominent role in Mother 3. But I'd be rather preferring Paula as Ness's Echo - yet she's now in his FS... bummer.
Anyway, I voted "No Viable Echoes".