I do like games with a buttload of playable characters, even when it makes no sense. Classic example I like to use, Kirby: Canvas Curse. Waddle Dee, Waddle Doo, King Dedede and Meta Knight do not fit in the story, ever, but you can play as them!! ...!!!
But I disapprove of Daisy altogether, and don't want to think of what Bowser riding Yoshi would look like. The rest, of those, sure. Though, said buttload of playable characters only really has its charm if everyone is unique--and the point of Mario, Luigi, a Toad and a Toad isn't that you can play as them. It's that four people can play simultaneously.
I don't like the idea of two nameless Toads all-a-sudden being in, myself. I doubt they're placeholders, but if they are, my votes are for Toad and Wario. Toad wears blue and Wario wears yellow. Red, green, blue, yellow. Like old times. Like current times. Only better.