I'm going to have to disagree with Terlor's answer here as when I was breeding for a Sheer Force Nidoran ♂ I got a Nidoran ♀ along the way. So in other other words you can get both Nidoran's when breeding a male one.
It is related to Nidoran♀ and, through Ditto, can lay Eggs that contain either Nidoran♂ or Nidoran♀.
Source: Personal experience + Bulbapedia page on Nidoran ♂