Ive noticed that too, Scylla! Once you think about it, Pokémon is actually quite weird. I mean, its really creative with the animals and stuff but... seriously at least get the genders right!  Like how can it just change to all male after its was already male and female. I just don't get it! X/

*breaths heavily* Me being a HUGE Pokemon nerd, I'll explain the nifty bits.

For the gender ratio, it's more like this is the only gender found. For some reason, Pokemon is really weird about what has been discovered and what not, and usually very vague. 

For Salandit, it's like how in real life male birds have colorful feathers and female don't. Only Female Salandits just have the traits to evolve into Salazzle. There are many Pokemon like Salazzle, like Gallade.

Pokemon can breed with others not in their species, though they have to be in the same egg group. For example, you can get a rufflet by breeding a ditto and a rufflet(Dittos can breed with practically anything).

For Primarina, Males in real life usually look very pretty to impress females. This is probably the case of Primarina. And for a more technical response, this is a habit for most starters. I can't think of a starter that doesn't have this ratio--Or at least very similar ratio.