Hey guys it's me there been a little disagreement between whether Rosalina is a princess or not DaisyFORFUTURE said to me Nintendo hasn't actually called her a princess and I completely AGREE with her theres has been good counters in this argument and DaisyFORFUTURE specified serious Nintendo wikias don't call her a princess so I recently sent as message to one of the Founders and Admin of Nintendo Wikia and this is what this what they left on my wall and i've got to say this is a great argument check it out!
Rosalina's status as to whether or not she's a princess can be a tricky thing. If you go by strict ingame canon without making any intuition into her background, she is never explictly declared a princess in most games but don't quote me on that this doesn't prove she isn't a princess. Second, her creator Yoshiaki did state and quote "We'll introduce a new princess in the series soon but she'll be divergent compared to Princess Peach and other females in the series" -Yoshiaki.
This statement was given in a conference almost a year before Super Mario Galaxy's release and her debut. Since there was no other princess introduced he was referring to Rosetta who we call Rosalina in english terms. Masahiro Sakurai creator of the Super Smash Bros. Series stated "Looks like another "princess" will be joining Princess Peach on the battlefield." Fans didn't know whether he was referring to Daisy or Rosalina but it was clear the princess was talking about was Rosalina when a trailer for Smash Bros. 4 revealed that Rosalina and Luma were being added to the roster. And the Super Smash Bros. Ultimate Guide even refers to her as a princess in her description and this wasn't PRIMA since the series never had a Prima Guide series. The clues in Super Mario Galaxy reveals her presumable home looking like a castle and her mother figure depicting a woman with a crown visually elucidating a female monarch convinces and partially proves that she is a royal though being gone for so many years along (she's much older than she was in the storybook) this is validated her claim to the crown is symbolic of her royalism and to where she was born and raised before becoming the mother of the lumas. This could the reason why she isn't commonly refered to as Princess Rosalina because she no longer resides in her kingdom and lives with a family of orphaned lumas as her new family this is why the name Rosalina was popularized. Although she would still technically be a princess because even if she doesn't reside in her kingdom she'll still retain a spot in a royal family tree. And even if she isn't called by her title by some sources doesn't mean she isn't a princess. So to answer your question the chances of her being a princess are immense due to quotes from partners and designers of Nintendo itself and verifiable evidence seen in Super Mario Galaxy and references spotted in spin-offs such as Rosalina's airballon seen on Royal Raceway along with Peach and Daisy's airballon reference for example and the chances of her not being a princess is quite insubstantial due to lack of evidence claiming she isn't using statements such as Nintendo themselves not calling her a princess or that she isn't called by her title like Peach and Daisy they're fair arguments but make very poor counters in debates especially if the statements are used a redundancy amout of times.
I think this was a fair statement comment and tell me do you think this a good counter.