Remind me when Pokemon was Shoujo? Oh wait, it never was. Why do you CARE the gender of who wins a Pokemon League? Assunta never had any personality and never even met Ash+co prior to that so her winning would just be as pathetically written as the guy who won Kanto, and the one who won at Johto. Cynthia's the Sinnoh Champion, so females DO win Leagues. Quit turning this into a gender thing and open your eyes. No character is entitled to anything in this Anime. Wanna know what that means? Female characters aren't entited or deserving of a League win, since they never earned it. If Tobias was a girl, he would still be a major asspull character written by the writers to stop Ash winning.
Even if a female character wins, the ONLY reason you should like it is if its a rival, and not some random person who Ash never battled, met, or WE never even heard of up till the point she wins. If one of Ash's female rivals wins, that's good. NOT because they are female (that's a pathetic reason to like it) but because its a character we've seen from near the beginning, they would have a personality, and they would have shown battle-feats unlike any expies of the guy who one at Kanto, the guy who one Johto, or Virgil. So long as the character who wins is a rival, I really don't care about their gender and neither should the rest of you. Had, say, Nando beat Ash in a really close battle and won the Sinnoh League, then that would have been better than seeing Darkrai and Latios curbstomp their way to victory. If Bianca won the Unova League, I would be glad that she won rather than a league rival with no real personality who would show up at then last minute to win (Virgil, Tobias, and Tyson come to mind. Ritchie was basically Ash with a brain, so saying he had no personality would be saying Ash doesn't). Her being female is the LAST thing on my mind. The fact she debut in episode 13, we've seen her fail but manage to work on her weaknesses, and trained up her Pokemon, would be the only thing I actually care about.
In short: Gender is trival. The gender of whoever wins a League is not important. How comes 2 of the 3 Grand Festivals were won by girls? The only one won by a guy was Robert...who had no personality and was basically 95% filler. Even at the GF, Nando was the only guy in the semi-finals. Oh, so you guys complain that Leagues are male-dominated yet have no problem with the female-dominated Contests...seems equal, huh. Not that I care about the guys at the GF, since I don't care about gender roles and gender outright in the anime. But you cannot deny that Pokemon Contests being female-dominated (To recap, the only major male coordinators were Drew and Nando. Harley could be considered one. Kenny isn't since he lost in the appeals round of his GF and shows little battle/contest-feats compared to the others) is no different to Pokemon Leagues being basically male-dominated. Remember, Kenny is technically Dawn's ONLY male rival. In fact, Nando was more of a rival to Zoey than to Ash or Dawn since outside of Nando's debut, he and Dawn never battled once.