I know my third party additions are unlikely, but I'm hopeful enough to include them in my roster.
Row 1: I don't think Toad is a good choice for a new playable character. Beside, Toad is already a special move for Peach, that should be enough. For a sixth Mario representative, not sure if it needs one or not, thought I guess Paper Mario would do, although to be fair, I'm starting to doubt that we need a sixth Mario representative.
Row 2: Dixie Kong would be okay, but I would prefer King K. Rool over Dixie Kong since he has more potential for being unique and Dixie Kong would work better as a pair team with Diddy Kong. Still, she is better then Kamek, who is not a good choice at all and not a character I would use. So if we have six on this side, it should be Donkey Kong, Diddy Kong, Dixie Kong, King K. Rool, Yoshi, and Wario.
Row 3: Eh, not really a fan of the two newcomers choice. I guess the fifth one should be Vaati, but I'm not incredibly familiar with The Legend of Zelda, so I'm not sure who should represent it.
Row 4: As much as I would love for Mewtwo and Lucario to come back, I doubt both of them will return for then next game. Of those, if one of them return, I lean towards Mewtwo, since his first appearance was in a video game. There should not be two Pokemon Trainers as playable character, that would be a waste of space. Ditch Hilda and replace it with a 5th gen Pokemon character.
Row 5: Perfect.
Row 6: Is it seriously necessary to have Samus and Zero Suit Samus as separate characters? I like them as they are, together, accessed by a Final Smash. I like the other choices, thought.
Row 7: Perfect.
Row 8: I'd be okay with Tom Nook, but I don't know what Andy would do to represent the series as a playable characters. Then again, I'm not familiar with the Advance Wars series.
Row 9: Balloon Fighter is not going to happen, although it would be neat if it did. The rest are good choices, thought.
Row 10: Tails is not a good choice for a 4th third-party character. Bomberman or Pacman are far superior as they have much more potential to be unique.