For some reason I haven't posted on this thread yet. Anyway here are my thoughts on the potential DLC characters.
NEWCOMERS
King K. Rool - Probably in my opinion the biggest and most notable character that hasn't been added to Smash yet. He is my #1 most wanted newcomer for Super Smash Bros. Offers a wide set of moveset potential such as his blunderbuss, krown, and helicopter pack plus he is a heavyweight character that is lacking in the roster. His trophy description mentions him being the equal to DK like Bowser is to Mario and that has a lot of meaning there. Meaning that K. Rool will always be relevant to the Donkey Kong Country series despite not appearing in Returns and Tropical Freeze. Another attribute of K. Rool is his different personalites. In DKC 1, he is in his default King look, DKC 2 featured K. Rool as a pirate kaptain (Kaptain K .Rool), DKC 3 had him as a mad scientist (Baron K. Roolenstein), and DK64 featured K. Rool in the final boss fight as a boxer (Krusha K. Rool). He can have four different palette swaps for each costume. Also, the DK series is in need of at least one newcomer (two in my mind). If Mario and Zelda can have their respective villains in Smash, why not Donkey Kong? Also to note, the head guy at Retro Studios, Michael Kelbaugh, has followed the Kremling Kampaign within the last month.
Dixie Kong - Dixie is another character from the DKC series that has starred in both DKC 2 and 3 back in the 90's. And now Tropical Freeze has reintroduced Dixie to the main series after Retro Studio's revival of the series. Dixie is currently my #2 most wanted character for Smash. She may not have the potential like K. Rool, but Dixie can be unique in her own way. Her ponytail is the biggest attribute for Dixie. She does a lot of things with the ponytail like attack with her hair and allowing her to slow her descent when falling. And also the bubblegun from Tropical Freeze and potentially her guitar too. Some think that Dixie could be a semi-clone of Diddy since the two are similar size, but I hope it won't be the case. I really believe that the DK series absolutely without question deserves two newcomers. Both K. Rool and Dixie are very well-known characters of their series. We've seen some of the other series in Smash complete their core cast. Mario has Mario, Luigi, Bowser, and Peach for their core cast and the Zelda series as well with Link, Zelda/Sheik, Ganondorf, and Toon Link. It would be very satisfying to see DKC get their core cast in Smash with Donkey Kong, Diddy Kong, King K. Rool, and Dixie Kong.
Isaac - Now to my #3 current most wanted newcomer, Isaac. Right here is an interesting case for Golden Sun's own Isaac. There was no sign of Isaac or Golden Sun content in the 3DS. No trophy or music. Not even the Isaac AT was found there on the 3DS. Now on the Wii U version, GS not only gets the Boss Scene/Final Boss theme back on Norfair, but it gets more content in another song found on Palutena's Temple as an unlockable track. Isaac was one of the best Assist Trophies in Brawl and has the potential to make the upgrade to playable character like Little Mac in this game. So far, there is no sign of Wii U exclusive ATs, which bodes well for Isaac. For his moveset (not that knowledge about his games), he wouldn't be just another swordsman character. He can use Psyenergy for his attacks and could be able to manipulate the ground and plants as a Venus adept. Golden Sun is a well-known series from the GBA era that deserves representation for a playable character.
VETERANS -
Wolf O'Donnell - I think the next veteran to be included for DLC could probably be Wolf. Wolf was a really good character in Brawl and was pretty unique compared to Fox and Falco. A lot of people think Wolf is a semi-clone, but I don't think he is at all. The only things he shares with Fox is the concept of his special moves and the Final Smash. Since Fox has Wolf's side special for one of his customs, they could give Wolf a new side special or try to tweak to make it different. Still baffling that Wolf didn't make the cut initially because I thought Sakurai liked Wolf and wanted to add him to Melee, but he didn't. Regardless, I think Wolf has a good chance since the new Star Fox game is coming within the next year or so some time and could help advertise the game.
Ice Climbers - Voted for these guys even though their chances for DLC is slim. It's hard to believe that they were working in the Wii U version just fine, but the 3DS led to them being cut. Pretty unique character and concept. Would like to see them back for those who were mains of the ICs. I didn't mind playing as them at times.
Lucas - I'm not that huge of a Mother fan, but I would like to see Lucas return. Ness does his PK Freeze for a custom special and it makes me wonder what they could do for Lucas. It probably would be best to try and differentiate Lucas from Ness some more. Mother does deserve two reps in Ness and Lucas.
Snake - The first 3rd party character to ever make it into Super Smash Bros. and opened the door for other third party characters such as Sonic, Mega Man, and Pac-Man to get into Smash. A really unique and serious character that fit in a cool way with Nintendo characters. His moveset was especially unique and not much should be changed. Snake was a character that I enjoyed in Brawl and the codecs as well were fun and entertaining.