It sucks there isn't a Echo Pack because if we can't get that many unique Nintendo reps as DLC, than at least it would be nice to have some Nintendo Echos. Here is who I would want in a Nintendo Echo focus pack:
/Medusa (Medusa could be her own unique fighter, but she could also work as a Palutena Echo with her having a similar body build and just making her attacks dark instead of light. Plus they could give Medusa some of Palutena's custom Specials from Smash 4.)
/Funky Kong (Easy and cool DK Echo to add.)
/Dry Bowser (Same as above.)
/Demise (Ganondorf or Ganon is the reincarnation of Demise so it would make sense to have Demise as Ganondorf's Echo when you see it through that retrospect. And Demise also has a sword so they definitely could make that work.)
/Leon Powalski (To give us another Star Wolf member and to balance things out with Star Fox and Star Wolf having a equal number of fighters in the roster. I feel like Wolf fighting Fox and Falco alone isn't fair even for a bad guy.)
/Black Shadow (Black Shadow would play exactly like Melee Ganondorf pretty much.)
I would have added Dixie Kong to the list as a Diddy Echo, but I feel like she deserves the semi-clone unique fighter treatment instead. But yeah, that's what I would go with for a Echo Pack.