Your example, Zasalamel, is the best one. Regardless of all that you've said against his sudden appearance. He complements my own point rather well I think.
He is unique, he offers a play-style that is fundamentally different from all the other characters, frankly I'm a little surprised people here are still going on about clones at this point. There haven't been any cloned characters (mimics or CAS types don't count) for a long time.
Soul Calibur 3 had a massive roster compared to the others along with the various CAS options that were new at the time. This and the various glitches were confusing to the larger and more inexperienced part of the player base at the time and that probably explains why it didn't do so well competitively compared to the more streamlined casts of Soul Calibur 4 and 5.
Take a closer look at Tekken Tag Tournament 2. If that isn't confusing to any size player base I don't know what is. This is why I said not too many at once. Make sure players have their chance to learn effectively without being constantly surprised or overwhelmed by better characters or players they don't know. Players do like to make up excuses for losing and they have vivid imaginations. This is where the single player modes and the story elements come into play.
They do need improving, but I do think giving players some time with additional characters could've worked, even without arcade mode endings and a more complete story mode. Unfortunately at this point I'm not sure any of that matters. I'm not so sure people will accept much less than a complete package at this point, if just the additional characters ever had a shot at all, but dwelling on that won't make it any better.
Ignoring that then the most unique characters like Zasalamel might just be good enough though. If I were to suggest some more it would be Yun-Seong or Hwang/Assassin, Cassandra or even Sophitia and Seong Mina or maybe Rock. Those last two in particular always had a hard time getting in, so maybe more completely new characters like say Bangoo is a better bet, there's always Talim.
The story elements look more essential everyday we wait, which does not help their cause without them, so without completing the stories of every character including any additions (maybe add some new match modes too)... I'm not so sure people will want to buy into it let alone back into it. Not to mention all this clone talk on top of everything. If there's one thing I'm definitely not saying, it's that it would've been easy, but worth it in the end? Well, I always hoped it could be, but I guess really I just wanted to play Lizardman again (but don't forget to give him back his hat)... Here's hoping.
And The Apprentice too... But if they give just his style to another character I'll never forgive them... Probably
