Imma be honest, I would've taken the Brawl tag-team over this current timeline. I understand the sentiments of some here that it'd keep both Dixie & Diddy from showing their respective stuff, but just consider how things unfolded as later Smash titles came. With Smash 4, "duo" characters had to either be split apart or axed completely (both in
's case) in exchange for a functioning portable Smash. Zelda, in particular, had to be split from Sheik, which resulted in the two getting tweaked, fleshed out movesets. It actually worked well, & the devs are sticking with it for Ultimate, & likely for the rest of time. If Sakurai's intent with our girl was indeed a tag-team with Diddy, then I say it's safe to assume they'd have worked more like Zelda & Pokemon Trainer & not so much like Ice Climbers. The kongs would've fought separately, possibly summon each other for an attack here & there, & just tag in & out via down-B.
Yall' can piece up where I'm going with this...
Brawl introduces Diddy & Dixie as a tag-team. I & others from my generation would have our first big hands-on experience with Dixie, & she's firmly solidified as a classic, if maybe dependant, Nintendo All-Star to many.
Smash 4 rolls around, & it's universal changes see Diddy & Dixie split apart (but never split
up, it's all bout' commitment). Now their flying solo, & the Smash team delves more into each one's individual skills/tools.
Ultimate drops like a nuke on an already successful system. Everyone is here, with a mess of new faces on the way, DK/Rare fans finally get K. Rool & Banjo in the green...except Dixie's actually there, & we wouldn't even have to be talking about this right now.
I could be wrong, of course, & I'm not the first to make this observation. Just think that in some alt. universe, we're all probably having a ball pitting Dixie in battles with crazy characters like Solid Snake, the Duck Hunt dog, Ryu, & Sans Undertale.