Oddly enough some of the clones were complete replacements, like Young Link, Falco, and Dr. Mario(who all had different moves as of stuff from Ultimate, so definitely couldn't be Echoes) from the start. Lucas wasn't one of those, but plays differently anyway. Just like the normal series. Dark Samus plays similarly to Samus, but has new AT moves.
Echo doesn't seem to be a thing in the game, as they're just forms of Clones. Even then, it wouldn't matter, cause no two characters play alike. They all have actual differences intentionally to flesh out the cast. A lot were just mainly model-based clones. And you can bet certainly stuff came from other character. Mewtwo's ability to float as a second jump always came from Ness first. Shadow Ball is still clearly created from Charge Shot. Ganondorf even uses his more regular cloned moveset, but he has no Sword to use so uses a makeshift Phantom Ganon Trident for his Smash attacks, respectively. Strangely he's more canon in Smash Remix than in Ultimate cause of that. XD
Basically, don't expect anything close to Daisy, Dark Samus, or Richter in Smash Remix. They're actually more different than that. That's how you can tell the Clones are fairly changed up/feel unique.