All the playable characters in Brawl are main characters in their respective franchises. Some of the characters you listed , like Tom Nook, Daisy, and Trixy, are assist trophy material at best. Banjo is impossible since Microsoft owns Rare. Mike Tyson is a real person. ROFL no. Petey and Ridley are bosses. They probably always will be.some characters have to be in it like megaman, tails, A better pokemon that jigglypuff, GOD DAM!
some fun characters would be geno, tom nook, mr resetti, leon, Banjo Tooie, paper mario, petey piranha, Trixy Kong, Slippy, Mike Tyson, daisy, ridley, midna/fairy.
I really hope they put someone from animal crossing in, even though it would be impossible to do,
they also need to put geno and banjo tooie in, since they are such good fits.
I think of the characters you listed, Paper Mario and Midna have the best chance. Geno is a minor character in one game AND a property of Square, so I don'r think he'll ever be more than an assist trophy if anything at all.
I think the best candidates for new characters in a future Smash game are some of the main characters who are assist trophies now such as Lyn, Isaac, Lil' Mac, and Saki and maybe a few very popular third parties like Megaman and Ryu.