Pika Hikari KT said:
I've always thought it was to counter any Fighting types. Poison is resistant against Fighting attacks, right?
My understanding of the use of Nidorina was that although it's clearly a poison type, it's "relatively normal".
Also, poison being resistant against fighting doesn't seem apparent. Otherwise, the use of a Pidgey or a Girafarig would have allowed the type advantage (even though in the game, Normal would cancel the Flying and Psychic resistances). Anyhow, it might be indirectly similar to Blain'e Rhydon, where the conditions match it's parametres. Rhydon can resist the large temperatures of the volcano, and Nidorina is ... as normal as you can get.
Not only that, but Whitney, supposedly having a gym (and farm) full of pokemon, would have access to more than 3 (though she clearly could have carried only 3 pokemon, which would force her to use Nidorina at the time anyhow, especially since it was an offday originally). Or you can apply the fact that Whitney carrying one is completely reasonable in general. So the style may simply be "start off, and get progressively better". Of course, Clefairy getting an unlucky Metronome was another thing, but Miltank having a larger amount of power is rather reasonable, because of the similar of focus of power it has (aka a team leader, or something).
I wanted to see this episode again, any language really xD, but there were so many episodes in this series that I missed most of it.
The power difference is reasonable, to say the least. Whitney's a nice gym leader. Though, it would seem strange that the large clumyness and cluenessness is within the same person that has a well focused powerful Miltank.