Actually, I believe the answer is simply Bonesy McBones, being as he's the one you challenge in the game of bones.
Going with the first part of the question, "this swamp dweller," which is singular, the answer would have to be just ONE person/character. The whole "Who are they?" thing is just the usual form pretty much any trivia question takes on.
Also, his
Subetapedia entry states that he claims to hail from a swamp.
That's my reasoning, at least. Take it or leave it as you please.