The whole concept of Echo Fighters is pretty nebulous, and personally I think they should be allowed to have at few more distinct moves compared to, like, Daisy or Richter being glorified alts. That said, I think it'd pretty concrete that Echoes need to share the same basic skeleton and body type, even if the animations are different. I'm no DK expert, but Dixie's hair looks a fair bit bigger and more involved than Diddy's tail. I dunno, I feel like that would be enough extra rigging that she'd have to be a semiclone at best.
With Funky Kong, he seems like he's decently Donkey Kong-shaped, but maybe the surfboard might give enough extra rigging to throw things off. That said it's not actually part of his body, so I'd assume it's fine. That said, while Diddy and Dixie are most certainly different characters in the games, I don't actually know how Funky Kong plays. From what I remember, he mostly plays like DK in Tropical Freeze, but he also incorporates aspects of the other playable characters to make him the designated Easy Mode character. But I'll have to double-check that, because I've only read a bit about the series and I haven't played any games or watched any videos