I was lucky enough to have Mario Galaxy save file and get her pretty quick but MAN if you didn't have one it must've taken forever to unlock her. Now I wonder if there might be a catch with this. Like could you play one cup in 50cc the whole time and unlock all the characters or maybe each character is assign to a class but not a specific cup? Like in order to unlock Rosalina you would have to play 100cc but it could be any 100cc cup. Haha maybe I'm over thinking it but I'm excited like you said, some of the other characters were super troublesome to unlock.
What I'm wondering is if there's a set pattern of characters that every game unlocks, or if it's completely random. Like person A on their game unlocks Wendy O. Koopa first and person B on their game unlocks Lemmy Koopa first.