I'm gonna be honest, I don't care much about cloning or moves that only fit the character based on their game history, there are only 5 characters slots to be filled, I would personally prefer to see characters that fill voids that Brawl is currently lacking in, or could benefit from.
So far I really have no desire to see Dark Samus integrated into P:M over Ridley, as so far I see Ridley filling an aerial master void that could be quite interesting to see, but don't really get what Dark Samus would be, other than clone this and clone that. If I wanted to play Samus, I'd play Samus, if I'd want to play Wolf, I'd play Wolf.
At the same time I am not bad-mouthing D-Samus, I'm just saying I don't see what she/it would do in P:M that we don't already have from other characters. Again, this is why I am an Issac fan, because in my mind I could see them integrating him with all charging specials to represent his three tiered spells, and thus having a fast character with very quick but low powered moves, but with the ability to charge them into KO moves. I know that if included that will probably not even be what Isaac will end up being, but it helps me see potential.
Maybe if Dark Samus fans would explore what she/it would give to P:M that it is currently lacking or could benefit from, more people may rally behind her/it?