Chief Mendez
Smash Master
Well, let's see...there are 2 (count em') games based off of the differences between the Mario Bros., Luigi has his own full-fledged mystery/action game, and in several other places, Luigi is explored in contrast to Mario.Daisy being version two of Peach isn't true, they are not even from the same place or proven to be related. Sure they play similar roles but thats it. Thats just like saying Luigi=Mario.
Look, this is the MARIO SERIES, not Final Fantasy. Debates over who has the richer character or whose personality is differential don't really work all that well. But that's not the point.
What is is this: Daisy never does jack****. Do you have any nostalgic moments of cool things Daisy did in a game? I can remember Luigi being denounced by his biggest fan, I can remember Wario beating the snot out of endless baddies in the pursuit of wealth, I fondly remember stomping that first Goomba in World 1-1...but I can't think of any notable Daisy-moments. That's why she won't be anything but a fan-serving costume change.