I understand the confusion. After all, the ratio is 87.5% male, 12.5% female.

But that ratio was never meant to represent how masculine or feminine the Pokémon would be. That ratio was meant to keep the starters rare and difficult to breed.

Feminine starters aren't new. Chikorita was the very first feminine starter. With its necklace, leafy ponytail, and suffix "ita" in its name, Chikorita leans towards the feminine side. Its final evolution is soft in appearance with a big pink flower adorning its neck.

If Game Freak designs starters with a more feminine approach, it's probably because they want to mix it up with a bit, make their pool of starters more diverse. Absolutely nothing wrong with that.

Personally I think Brionne is an adorable Pokémon and it doesn't bother me at all that it could be male. Why should it? I've seen female Machamp, male Bellossom, male Gothitelle, female Conkeldurr, and the list goes on. We should know by now that gender doesn't mean much in Pokémon games. Its only real purpose is for breeding.