As part of its ongoing efforts to promote every single Pokémon out there, The Pokémon Company has shared special content dedicated to Nidoran:
Did you know?
Nidoran♂ has developed muscles for moving its ears. Thanks to them, the ears can be freely moved in any direction. Even the slightest sound does not escape this Pokémon’s notice.
Nidoran♀ has barbs that secrete a powerful poison. They are thought to have developed as protection for this small-bodied Pokémon. When enraged, it releases a horrible toxin from its horn.
Source: @Pokemon