There is something I want to add to the Pokeradar Information. It appears that both Nidoran M and F both also appear on Route 201, and when going after them with the PokeRadar, almost seem common rather than uncommon. They also have a minimum level of 3, which is what I caught them at. They also seem to have a chance of attracting another Nidoran of the opposite sex with the same nature, but different characteristics.
Both the Nidoran M and F I caught have a Calm nature, and they have different characteristics.
Just something I thought I would say.