Nidoran♂ is a small, quadrupedal, mammalian Pokémon. It is pinkish purple with darker patches. It has large, spiny ears with teal insides, oversized front teeth, and red eyes. Its back is covered with three lines of large spines that can release potent poisons if threatened. The center line of spines is taller than the other two. The size of the long, pointed horn on its forehead is indicative of the strength of its venom. Nidoran♂ is a male-only species.
Nidoran♂ constantly listens for the sounds of approaching enemies with its large ears. Said ears have unique muscles that allow them to be moved in any direction, and even the slightest sound does not escape Nidoran♂'s notice. In order to listen to distant locations, it flaps its ears like wings. When angry, it extends its toxic spikes and charges, stabbing with its horn to inject poison. Nidoran♂ is brave, and will risk its own life to protect Nidoran♀. Nidoran♂ lives in open spaces, such as savannas and plains.
In Wherefore Art Thou, Pokémon?, a Nidoran couple was in love with one another, much to the dismay of their Trainers, who hated one another. After the battle with Team Rocket, upon which he kissed Emily's Nidoran♀, Ralph's Nidoran♂, nicknamed Tony, evolved into a Nidorino.
In Leading a Stray!, multiple Nidoran♂ assisted a Luxio in its efforts to help a Wailmer trapped in the sewers.
Two Nidoran♂ debuted in Pokémon Fashion Flash as some of the Pokémon seen on Scissor Street.
A Nidoran♂ appeared in The Breeding Center Secret.
In Showdown at the Po-ké Corral, multiple Nidoran♂ were living at Professor Oak's Laboratory. These Nidoran♂ were colored the same way as Shiny Nidoran♂, but they predated the introduction of Shiny Pokémon.
In Pikachu's Vacation, a Nidoran♂ was at the Pokémon Theme Park.
A Trainer's Nidoran♂ appeared in Bad to the Bone.
A Valencia Island variant of Nidoran♂ appeared in Poké Ball Peril.
In In the Pink, a pink Nidoran♂ was a resident of Pinkan Island. Team Rocket attempted to capture him and his female counterpart, but they ended up being chased off by a pink Nidoking.
In The Power of One, a Nidoran♂ sensed the disturbance caused by Lawrence III.
A Nidoran♂ appeared in the Japanese credits of Pikachu's Rescue Adventure.
A Nidoran♂ appeared in The Chikorita Rescue alongside a Nidoran♀.
In Going Apricorn!, a Nidoran♂ was fed by Tracey at Professor Oak's Laboratory.
A Nidoran♂ appeared in A Farfetch'd Tale alongside a Nidoran♀.
In The Fortune Hunters, a Nidoran♂ was stolen by Butch and Cassidy.
A Nidoran♂ appeared in Celebi: The Voice of the Forest.
In Fangs for Nothin', a Nidoran♂ was an inhabitant of the Dragon Holy Land.
In Showdown at the Oak Corral, a Nidoran♂ was living at Professor Oak's Laboratory.
Multiple Nidoran♂ appeared in the opening sequence of Destiny Deoxys.
In Beg, Burrow and Steal, a Nidoran♂ was a resident of an underground paradise.
A Coordinator's Nidoran♂ appeared in Mean With Envy.
A Coordinator's Nidoran♂ appeared in Hi Ho Silver Wind!.
In Lucario and the Mystery of Mew, multiple Nidoran♂ were living in the Tree of Beginning.
A Nidoran♂ appeared in The Green Guardian.
A Nidoran♂ appeared in Off the Unbeaten Path.
A Coordinator's Nidoran♂ appeared in Harley Rides Again.
In Odd Pokémon Out!, a Nidoran♂ was a resident of Camomile Island.
A Nidoran♂ appeared in Not on MY Watch Ya Don't!.
A Nidoran♂ appeared in Pokémon Ranger and the Kidnapped Riolu! (Part 1). Two additional Nidoran♂ appeared in the follow-up episode.
Multiple Nidoran♂ made a cameo in Arceus and the Jewel of Life.
A Nidoran♂ appeared in Cilan's demonstration in Mystery on a Deserted Island!, where he evolved into a Nidoking.
A Nidoran♂ appeared in Grooming Furfrou!.
A Nidoran♂ appeared in a flashback or a fantasy in The Forest Champion!.
Multiple Nidoran♂ appeared in Diancie and the Cocoon of Destruction as residents of Allearth Forest.
In Pikachu and the Pokémon Music Squad, a Nidoran♂ residing in a forest.
A Nidoran♂ appeared in a flashback in A Watershed Moment!.
A Trainer's Nidoran♂ appeared in a flashback in Alola to New Adventure!.
In I Choose You!, a Nidoran♂ was taking shelter from the rain in a cave alongside Entei.
A Nidoran♂ appeared in a flashback in Enter Pikachu!.
In Dreams Are Made of These!, Goh caught a Nidoran♂ during a Pokémon Orienteering competition. He has since made further appearances in Pokémon Journeys: The Series.
A Nidoran♂ appeared in Healing the Healer!.
A Trainer's Nidoran♂ got stuck in Gulpin's giant ball in A Rollicking Roll….
A Trainer's Nidoran♂ appeared in Take My Thief! Please!.
In File 1: Red, a Nidoran♂ was seen in Professor Oak's introduction, while another was under the ownership of Red. Red used his Nidoran♂ during his Gym battle with Brock.
A Nidoran♂ played an important role in the third episode of Pokétoon, helping Tsubomi and later becoming her starter Pokémon.
At the end of the episode, he was revealed to have evolved into Nidorino.