Melee Clones aren't officially considered Echoes, but I would personally consider their Melee States Echoes. They were all De-Cloned from there, mostly via Animation for Young Link and Pichu, Moveset for Falco, Ganondorf, and Roy, and Dr. Mario is the least changed. Dr. Mario is Ken Tier in my opinion. He has the amount of differences Ken has, a Borderline Semi-Clone, and the only thing preventing him from being an Echo is the fact that he was in Melee.
Except the term Echo exists solely in Ultimate.
They are literally and officially referred to as Clones.
There is no such thing as an Echo till Ultimate(and literally only could it loosely apply in 4, and at most, Dr. Mario still can count).
They fail to have the same bodyshapes as is. So beyond Dr. Mario, they're not "Melee style". They're just clones, because they used someone as a base and have similar movesets. Even Smash 64 did this somewhat(Mario was used for both Ness and Lucas, Samus was used for Falcon, and Kirby was used for Jigglypuff), and Sakurai never once called these clones either. Though to say the least, Luigi and Jigglypuff are close enough to be them. The other two are too far off, much like Wolf is.
Dr. Mario being in Melee isn't the only thing. He has way more attribute and move differences than Ken, which from our knowledge, attributes play some kind of role, but that's only something that Reggie said. Whether that's entirely accurate or not is unknown, but Dr. Mario and Ken are very very different regardless. The only thing in common besides using a base is same proportions. That's like it.
This is literally trying to rewrite history by using a really strange term that makes no sense, honestly. Nobody is saying Dr. Mario couldn't be an Echo necessarily(just there might be reasons why he isn't one beyond being in Melee, which does make sense). Dr. Mario did start off poorly, agreed. Funny thing is he's the only one close enough to an echo in Melee either way, since he barely is changed. The rest are too massively different to be even "close" to that.
Frankly, no, Ken isn't a borderline semi-clone. He's a borderline
clone, which are much less unique than a semi-clone(Isabelle is even closer than ones like Wolf, and Ness doesn't even come close to being a semi regardless of the base. But to be fair, he shared slight animations, less than Falcon too. You see thematically similar moves here and there at best).
Again, Echoes are just a subset of clones. They don't "exist" that early on. At best only in 4, and only two characters since Dr. Mario actually had fairly different stats(more than Ken did even then in comparison) that made him stay as a regular clone.