So, i have been wondering what is the criteria for a pokemon species to be entirely male or entirely female. Some examples make sense right away, like Miltank, Kanghaskan or Chansey line being entirely female, but not exactly everything is so easy...
Being aesthetically masculine or feminine doesnt seem to enough, as the Machamp line can be female while the Gothitelle line can be male, and there are more examples of generally masculine or feminine-looking pokemon being able to be both genders
I searched far and wide but couldnt find any video or post somewhere talking about this, so maybe there is no reason at all? I was basically wondering if there is any hard rule as to what makes a pokemon species be entirely male or entirely female? Of course i know there are different reasons for every single one of them, but is that a reason they do not share with another pokemon that does not receive the same treatment? (Like saying Throh is fully male because its masculine-looking while the same doesnt apply to the likes of Machamp or Conkeldurr)
From my experience there's usually a strong background lore reason for the things that gamefreak does.
So it could tie in to the create the pokemon is referencing or inspired by. Like you said pokemon like milktank make sense a cow is a female a bull is the male.
The only one I could never figure out, is why hitmonchan is a male only pokemon, that clearly should have been a gender evo split instead of a stat thing, very weird.
I mean hitmonchan's look is clearly meant to invoke a the look of a tank top/sports bra and skirt.
It even has "chan" in its name.
But back on topic you mentioned the pokemon Throh, while I didn't look that up I looked up its counterpart sawk and this what came up.
Sawk is based on Mas Oyama, a well-known karate expert and the creator of Kyokushin karate, and oni.
So like I said lore, Sawk is a male only pokemon because its designed and inspired by an actual guy.
edit: took a look at himonchan while I was at it, and it appears the case is the same, that is also inspired by a guy, this time a world class boxer.
So it seems the problem is just an unfortunate English name? idk, that pokemon will always be female to me that's my headcanon.