I would actually be fine with both Toad and Rosalina as DLC as long as there is DLC and at least Toad is included in that if not in the game proper. Both hold more relevance and actual playable status in mainstream games as compared to Bowser Jr., Waluigi and Daisy, which is why, like others, I'd now be putting Rosalina's chances above them all - especially due to her large status in not one but two mainstream games, and a third that she is now playable in, albeit as an unlockable bonus extra. She even has Galaxy-themed attacks as her specials, which sets her apart from Peach, so I could see her being at least semi-unique if she were to ever grace the Smash world with her Luma-inous presence - but Toad takes precedence first and foremost, and he has the potential to be a very unique character, unlike Jr., Daisy, and even Rosalina to a certain extent, who would likely be clones of Bowser and Peach, respectively; and Waluigi, who has the potential to be unique, but has never even been in any mainstream game period, and doesn't have the positive recognition to warrant a playable spot at this point, especially compared to the others. Paper Mario is, of course, a very possible contender as well, but still suffers from being Mario in Game & Watch form basically, and despite the potential for great uniqueness, this would likely get lost in translation as has been the case with several characters being clones of another (Falcondorf, anyone?), and I personally don't have high hopes, though it would be awesome.