With the double-feature inclusions of
and
in Smash 4, the Mario series as a whole had honestly gotten pretty much the biggest names for it on lock. The way I see it, there are currently three big avenues if there is to be expansion.
1) (Captain) Toad - The last major character of the main games, even if people may argue the major part. Toad has had a popularity since Melee when it comes to requests and seems to only be growing with each installment. The character identity, in my opinion, cements a specific character instead of some of the possible argument for it just being "a generic toad." There is nothing, inherently, that Captain couldn't be able to that any standard Toad could. With Treasure Tracker being one of Nintendo's more experimental projects of being a budget title and I feel that, if he continues being used as he has since inception within Galaxy, he will be a sizable contender for Smash 5.
2) Paper Mario - The RPGs are one of the best wellsprings for new content within the Mario name outside the mainline series. With that there are three "branches" with Mario's RPGs. Super Mario RPG which I find there to be a small miracle that we got so much as a Geno costume and I really can't find faith for Geno to appear in spite of his Brawl-era popularity. Mario & Luigi RPGs are the ones that Nintendo seem to push the most but... it lacks any big standing characters for it who AREN'T just Mario & Luigi that would be able to be brung up. Fawful was the biggest option but was killed off in the conclusion of Bowser's Inside Story. That of course, leaves the namesake of the very distinct incarnation of Mario who people clamor for a proper sequel. He's, of course, got a legitimate amount of power behind him in terms of requests which is only more in his favor.
3) Waluigi or Daisy - Mario's "multiplayer" spinoffs such as Party, Kart, and the various sports games are one thing that certainly could be a pool to get material from. All at hand being two thirds of
's forward Smash, two stages, and a handful of items (all from Kart). Both of these characters, as well, have a noticable amount of support behind them to the point of which Waluigi's popularity and "how hard he tried' being poked at, with tongue-in-cheek humor with his Assist Trophy's reveal. Now, I am considerably biased for Waluigi, but him making his steps to have already become an Assist Trophy, having far larger visual distinctness from the others of the series, being a more "zany" character with some more bizarre traits, and a seemingly larger fanbase among smash fans. Daisy is very much a popular character and a present rival for Waluigi in this niche, but I feel that he wins out in this situation.
And... I can't help but acknowledge
4) Nabbit - A... bit of a curveball. A character that sprung up as a small mechanic in New Super Mario Bros. Wii U and has stuck around longer than most expected. While not making the jump into Mario Party, Kart, or a standard Sports game, he did manage to be a stage hazard for the Mushroom Kingdom U stage and become one of the added characters for the Mario & Sonic Olympic roster. He has a level of a fandom, but he just doesn't seem to have a level of real impact in the series to be too large of a dog in the race.
Overall, with the main series now reaching 6 characters.. there is certainly a chance that Mario as a series won't get a newcomer as they did in Brawl, but I have confidence that it will come as it is still THE series for Nintendo and has some bigger names left to expand in.
Ugh, this is so embarrasing...
