discuss with love_machine011 the fuckability of grass types.
What you're seeing here is the association of flowers and ladies (and romance) in general. If you're going to make a pokemon with a flower adorning it's head (like Lilligant), your mind moves to people who would wear a similar adornment - high-class ladies - and include other elements of the style (e.g. the ball gown).
A lot of grass types, or more specifically flower pokemon, look feminine because the flower
itself is a feminine symbol and they extrapolated from there.
It's telling that all of the grass types just shown have both feminine (or at least high-class) and plant-themed names:
Tsareena - Tsarinas and to a lesser extent mangosteens.
Roserade - Roses and Maskerades. Notably this is probably the one most commonly depicted as a male.
Lilligant - Lily and Elegant.
Hell, even Venusaur ironically qualifies, being named both after the Venus fly trap and the goddess Venus, typically associated with feminity. So even what should be the obvious exception ends up having reference by dint of what it's name references.
I think its a crime that Psyduck hasnt gotten a Mega Evolution or a regional variant or whatever that giant shit in Sword and Shield was
If there's ever an Australian region, we need a platypus-themed Duck.