just like donkey kong originated from mario's roots, but then branched off, and the proof that he is related to mario is in all the spinoff games, because in donkey kong the game for nes, mario was known as jumpman, but was still mario, so this is evidence to prove that they are in the same series, but have subseries that qualify for smash bros. So rosalina would be from a subseries of mario called super mario galaxy, so the only reason there is the same symbol is because rosalina is not the protagonist in the game, it would be reasonable to put the same symbol only because she wasn't as important as mario...