Usually people say that Mary sue is Bloom. Because she is perfect, beautiful, a princess, strong.
But Bloom is not a sue like Flora.
Of course you can say how can Flora be a Sue? But I'll explain,
Reasons why Flora Mary Sue:
She is overrated!
It has the largest fan base. She doesn't have any haters. It's every Sue's dream to have a crowd of fans who will worship you 24/7. And every time I hear : Flora is the best fairy, Flora is beautiful, Flora is sweet, and so on. Her fans are the most annoying, if you say something bad about Flora, it will start: Don't touch Flora and a lot of angry smiles.
She's beautiful!
I do not deny that she is the most beautiful of all the fairies in their club. But this already pisses me off! Flora always has the most beautiful things and transformations. I also want to note that it is constantly present pink color. Whether it was wings, dresses, swimsuits, shoes, dresses, even the cat was pink.
She's perfect!
God, kill me, but she's always the most perfect! Her fans idolize her and yet hate other fairies. The only thing that makes it such a stupid character and beautiful appearance.