This discussions that has been going on all day is a little ridiculous.
Every single character can have a unique moveset, and in a perfect world they would. But we all know echo fighters are a compromise that allows us to get a character playable at the cost of their own unique moves. And that's still pretty cool.
While every character CAN be unique, not every character can be an echo. Only specific characters can line up move-wise to the original character. Dixie is one of those that would pretty much work. Yeah she could be unique, but she can also very easily be a slightly modified Diddy echo, just like Chrom is a slightly modified Roy echo. This makes it incredibly likely for her to get in the game versus incredibly unlikely. Characters like Isaac and Geno and Skull Kid would never be able to work as echo fighters of any playable character currently in the game. Therefore if any of them would get in they absolutely would need to be unique. Dixie isn't "competing" against those kinds of picks. She's competing against picks like Impa and Medusa who could also work as echoes.
And regarding the whole female fighter debate, that is also ridiculous to continue to bring up. Most fighting games, and video games in general, have a female character problem. We all know why. And as a massive crossover of various video game franchises, obviously Smash is going to by nature have that same issue. But despite that, there are actually quite a lot of female characters on the roster (both wholly female and characters that offer both male and female versions). Sakurai has done a pretty good job about inclusion in this regard.
I don't think a character being female alone should be what increases their chances to get into the game or not. Dixie should get a spot, but that doesn't mean characters like Isaac shouldn't. Etc.