Nidoran♂. Its horn is larger than the female’s and its Horn Attack is quite powerful.
– Ash’s Pokedex
Nidoran♂ is one of the few Pokemon with a non-alphabetic character in its name. Even though it seems to be the male counterpart of Nidoran♀, they’re considered separate species rather than just gender-differences within the same species. Though Nidoran♀ eggs have a chance of hatching into Nidoran♂, so that it can breed without using Ditto.
I always found it odd that Nidoran♂ is purple/pink while Nidoran♀ is blue. It feels like they’re backwards…
Stat-wise it’s got more of Speed and Attack.