You need to be a little more open-minded than just those choices.
Well who do you believe should be on this list that is not there currently?
Mario's only remotely feasible character is Captain Toad, whom I don't see that plausible to get in.
Yoshi's games really don't have much to choose from in the first place.
As Wario's entire structure revolves around WarioWare instead of his actual platforming games, who would be to choose from there? As much as I'd like to see the creativity around Ashley and Waluigi (whom Sakurai now dubs a Wario property), they're confirmed AT's and I don't see any current AT's getting an alternate playable character.
Likewise, Ridley finally ultimately and inarguably being confirmed as a boss put an end to any debate for him as a playable character in my eyes.
As a big fan of Kid Icarus: Uprising and even rarer, someone who played through the original, I don't see anyone else that could be and should be turned playable. Sakurai's getting enough harassment about the Uprising content as is.
Fire Emblem's characters have been Marth and Ike, the two characters to be Lord-tier in multiple games, Roy as a last-minute choice of a clone to promote his upcoming game, Robin who was a protagonist who technically represents a concept that was also in FE12 and was WILDLY asked for, and then Lucina whom was originally meant to be just an alt. Anna is the only other character who has put forth a big role in multiple games (In fact, being present in 12 of the 13) unless you count the minor appearances of Eliwood and Hector as middle-aged fathers for about a chapter each.
Pokemon with a full 6 feels justified, being a full party. The only "missing" feature is a pokemon from either gen 3 or 5, and a grass starter. With OR/AS on the horizon, Sceptile is really the last choice for a newcomer.
F-Zero, Pikmin, WiiFit, Animal Crossing, and Punch-Out!! feel complete in representation where they are at... and there's not much in the source material, if anything, that could be put into a new character. Black Shadow's one big hope was taking Falcondorf's moveset for a complete revamp for Sakurai's main.
Retro I left open because it's too unpredictable in the first place.
Third Party characters... I just can't see happening via DLC. I'm namely looking at DLC as what is being done to finish what wasn't capable during the development time. I stated that because of the circumstantial nature of how overhauled and reworked Mewtwo would have to be, he would take an immense amount of manpower and time. Judging by the "Spring 2015" deadline, that seems to be true. As such, if there was another 3rd Party character planned, I don't see them being unfinished and needed to be accomplished via DLC. There'd likely be some contractual issue if so.
Series who will have a character appear as its first newcomer, Isaac from Golden Sun (Barring him being a WiiU exclusive A.T.) being the perfect example, are open territory in regards to the list.