We're not sure how or why it happened, but Bowsette has become an internet phenomenon. This female version of Bowser was originally fan art that came out after the reveal of Toadette in New Super Mario Bros. U Deluxe, who becomes Peachette after obtaining a specific crown. Somehow, this led the internet to imagine Bowser with this crown and now we have a "sexy" version of Bowser.
Bowsette seemed to be an internet-only concoction and one that Nintendo seemingly doesn't want to be a part of, but it turns out that they may have come up with the idea before everyone else.
Fans who purchased the Super Mario Odyssey art book found out that Bowser was supposed to have his own version of Cappy, an ally of Mario who allows the Italian plumber to possess some enemies. In the art book, we see some story concepts that have Bowser with this faux Cappy that lets him possess other people and, you guessed it, he does indeed possess Princess Peach.
This version of Bowsette has a couple of features from the internet-made version, like the scales in the back, but not much else. The Odyssey version of Bowsette has red hair and a cap, while the internet version is blonde.
Also, the Nintendo version of Bowser is pretty tame when compared to the NSFW one that the internet has conjured up. The fact that it's still a meme right now shows its staying power.
New Super Mario Bros. U Deluxe comes to the Nintendo Switch on January 11, 2019.