I haven´t read the whole post but for me, the mandatory roster for the multiplayer Mario games should be at least these:
-Mario
-Luigi
-Bowser
-Wario
-Waluigi
-Peach
-Yoshi
-Toad
-Daisy
-DK
and depending on the characters needed for the specific game and/or nintendo´s lazyness, it can be extended to:
-Toadette
-Birdo
-Rosalina
-Diddy
That´s a main 10, extended to main 14 that should be inexcusable not to have them at this point in the series, as all those characters I listed are big parts of the Mario franchise or at least the multiplayer Mario games.
Also, while generics like Dry Bones, Shy Guy, Boo and the likes are nice additions, I´m all for the unique characters. So, while I wouldn´t label them as "main", I definitely prefer King Boo, Petey Piranha, Wiggler, Dixie, Funky, and the likes, that while they aren´t a "must" in every Mario game, they should be rotating and having appearances every now and then, instead of the baby overkill, generic characters or alternate versions of existing characters (Metal Mario and Dry Bowser, urgh...) I don´t complain if the babies or the generics are in as ADDITIONS but I do when they take the space of more deserving characters.
Also, the RPGS need to be counted too. Fawful MUST appear in the multiplayer Mario games, or else I´ll have fury.
EDIT: Also, character specific reasons shouldn´t weight that much. Sure, Peach was made as a damsel in distress, but it´s VERY easy to change the plot from "rescuing the princess" to "save a neighbour kingdom from their tyrant/invader" or "get the 7/8 plot relevant items that are guarded by their respective bosses". It´s not like it hasn´t been done before. Also, the "Wario and Waluigi have different moves" is stupid too, because it wouldn´t be the first time character´s abilities are balanced for gameplay purposes. Or don´t you remember back when Luigi couldn´t wall jump? Guess why they did give him that ability?
-Mario
-Luigi
-Bowser
-Wario
-Waluigi
-Peach
-Yoshi
-Toad
-Daisy
-DK
and depending on the characters needed for the specific game and/or nintendo´s lazyness, it can be extended to:
-Toadette
-Birdo
-Rosalina
-Diddy
That´s a main 10, extended to main 14 that should be inexcusable not to have them at this point in the series, as all those characters I listed are big parts of the Mario franchise or at least the multiplayer Mario games.
Also, while generics like Dry Bones, Shy Guy, Boo and the likes are nice additions, I´m all for the unique characters. So, while I wouldn´t label them as "main", I definitely prefer King Boo, Petey Piranha, Wiggler, Dixie, Funky, and the likes, that while they aren´t a "must" in every Mario game, they should be rotating and having appearances every now and then, instead of the baby overkill, generic characters or alternate versions of existing characters (Metal Mario and Dry Bowser, urgh...) I don´t complain if the babies or the generics are in as ADDITIONS but I do when they take the space of more deserving characters.
Also, the RPGS need to be counted too. Fawful MUST appear in the multiplayer Mario games, or else I´ll have fury.
EDIT: Also, character specific reasons shouldn´t weight that much. Sure, Peach was made as a damsel in distress, but it´s VERY easy to change the plot from "rescuing the princess" to "save a neighbour kingdom from their tyrant/invader" or "get the 7/8 plot relevant items that are guarded by their respective bosses". It´s not like it hasn´t been done before. Also, the "Wario and Waluigi have different moves" is stupid too, because it wouldn´t be the first time character´s abilities are balanced for gameplay purposes. Or don´t you remember back when Luigi couldn´t wall jump? Guess why they did give him that ability?