Bianca is a female rival to Ash.
There was also Katharine, who was friendly, but she had an episode and then we shall review only the figuration in the Unova League...
But for me the worst case remains Casey... This is the first Ash Female Rival's... She was cool... And it's not even gone to the league... To be replaced by an ugly girl fan of Fire Pokémon... The only flaw that I will give to the Johto League ...
I'm French, so I apologize in advance for my writing's mistakes in English. ^^
For me, AG is the best anime's period.
Quest Team Pokémon X : Hawlucha, Gardevoir Shiny, Blastoise, Gogoat, Tyrantrum and Delphox
Quest Team Pokémon Alpha Sapphire : Ninjask, Altaria, Azumarill, Sharpedo, Glalie and Blaziken
Quest Team Pokémon Blue : Nidoking, Pidgeot, Dewgong, Hitmonlee, Aerodactyl and Jotleon