Because for some reason when I started Ultra Moon, I got a Female Rowlet on the first go and when we battled Hau, his Popplio was Female too. I heard somewhere that Hau can have a shiny starter and that got me thinking about it.
Assuming like all other games I've played, the starters have all had 87.5% male to 12.5% female, or 1/8 chance of being female, in UM assuming these odds are the same, the chance of both you and Hau having female starters is approx. 1/64 chance. So pretty rare, but not unheard of.
Wait wuuuuuuuut, you got that too?! :O SAME HERE!! My Rowlet, Aspen, was a girl the very first time around, and Hau's Popplio was too! What are the odds? :O
I'm jealous, I don't think I ever got a female starter. Actually I only got my first shiny not too long ago, so I think I'm just extremely unlucky in Pokémon.
Hau received a female Popplio in my Ultra Moon playthrough. However, my Rowlet was male. My brother's Litten also turned up female, oddly enough.
When I played Sun, I got a Female Poppilo first try, throwing my original nickname for a male out the window (it was Timothy). I luckily knew of a perfect female nickname for Poppilo, which is Brooke. When USUM came out, I was dead set on a Female Poppilo. I soft resetted until I got my female Poppilo. I think it was about 10 times it took me.
The same happened to me! In UM, I got a female Rowlet off the bat and I was so happy that Hau had gotten a female Popplio! It was like, 'omg, besties!!'