Bowser Peach/Princess Bowser/Bowsette is a concept evolved from the trailer for New Super Mario Bros U Deluxe (thats a mouthful of a title that makes no sense since its on the switch) where Toadette is a playable character.
When Toadette gets a new item called a Super Crown
She turns into Peachette, which made people speculate as to whether Peach is even human or just an evolved form of toad.
A few days later this comic appeared by twitter user
@ayyk92
The idea here being that anyone who gets the Super Crown will become a Princessified version of themselves.
This has sparked a lot of fanart of this particular version of bowser, some appearing like this and others where she has red hair and dark skin.
She’s the waifu of the month it seems just like the gijinka of internet explorer was last month.
Marshmellowmilktea 