Nidorino is a light-purple, quadrupedal Pokémon. It has several darker purple patches across its body. It has large, spiny ears with teal insides, narrow black eyes, and a long snout with two pointed teeth protruding from the upper jaw. Nidorino has a ridge of toxic spines on its back and a long, pointed horn on its forehead. The horn is harder than a diamond and capable of secreting poison on impact. Its short legs have three claws on each foot. Nidorino is a male-only species.
Nidorino is independent, nervous, and fierce; and it is often described as violent and easily angered. It uses its ears to check its surroundings. If it senses a hostile presence, all the barbs on its back bristle up at once, and it challenges the foe with all its might. Nidorino's horn is as hard as diamond, allowing it to easily destroy boulders. It uses that horn to look for Moon Stones. The level of adrenaline Nirdorino has can determine how strong its poison will be. Nidorino live in hot savannas and plains.
In Pokémon - I Choose You!, a Nidorino was going up against a Gengar in a battle that Ash was watching on TV. Thus, Nidorino and Gengar were the very first Pokémon to be seen in the anime, excluding the intro.
In Fire and Ice, Ash battled a Nidorino during the Indigo Plateau Conference. He reappeared in a flashback in Friends to the End.
In Wherefore Art Thou, Pokémon?, Ralph's Nidorino, nicknamed Tony, evolved from Nidoran♂ after battling Team Rocket and kissing Emily's Nidoran♀, nicknamed Maria.
In The Heartbreak of Brock, Temacu's Nidorino was taking a stroll with her Nidorina.
In Restore and Renew!, Jessie pulled a Nidorino from the Rocket Prize Master and used him in an unsuccessful attempt to capture a recently-revived Aerodactyl.
In The Flame Pokémon-athon!, multiple Nidorino were at the Laramie Ranch.
Two Nidorino appeared in the banned episode EP035, with one appearing in a flashback.
In A Chansey Operation, an injured Nidorino was brought to the clinic.
A Nidorino appeared in The Breeding Center Secret.
In Mewtwo Strikes Back, a Trainer's Nidorino was defeated by Mewtwo while it was serving Giovanni.
In The Power of One, a Nidorino sensed the disturbance caused by Lawrence III.
In A Tent Situation, a Nidorino was at Professor Oak's Laboratory.
In Tricks of the Trade, a Nidorino was at the Pokémon Swap Meet in Palmpona.
Two Nidorino appeared in The Legend of Thunder!.
Multiple Nidorino appeared in the opening sequence of Destiny Deoxys.
A Nidorino appeared in Pokémon Ranger and the Kidnapped Riolu! Part 1 and Part 2.
A Nidorino appeared in Arceus and the Jewel of Life.
A Nidorino appeared in the opening sequence of Zoroark: Master of Illusions.
A Nidorino appeared in Mewtwo's flashback in Genesect and the Legend Awakened.
In Mewtwo Strikes Back—Evolution, a Trainer's Nidorino was at Old Shore Wharf.
||Nidorino, the Poison Pin Pokémon. The evolved form of the male Nidoran. Its highly developed horn is extremely powerful.
In File 1: Red, a Nidorino was seen in Professor Oak's introduction, while another was seen battling a Gengar.
In the game intro-like opening sequence for The Adventure, a Nidorino was battling a Gengar.
A Nidorino appeared in A Budding Dream, under the ownership of Tsubomi.
- Nidorino is one of the first two Pokémon to appear in a Pokémon battle both in the anime and in the games, the other being Gengar. This is due to their appearance in the opening animation of Pokémon Red and Green, on which the beginning of the first anime episode was based on, as well as the remakes.
- It is also the first Pokémon to be both seen and captured in Pokémon Adventures, in much the same way.
- Nidorino, along with Gengar (and, possibly, other Pokémon), originate from the old manga, Capsule Monsters, which is considered the ancestor to the Pokémon franchise.
- The Nidorino that appears in Professor Oak's introduction in Pokémon Red and Blue has the cry of a Nidorina.
- Nidorino's Shiny coloration is the same as Nidorina's normal coloration. Likewise, Nidorina's Shiny coloration matches Nidorino's normal coloration.
- Nidorino shares its category with Nidoran♂, Nidoran♀, Nidorina, Poipole, and Naganadel. They are all known as the Poison Pin Pokémon.
Nidorino appears to be based on a rhinoceros, porcupine, rabbit, mouse, or even a hamster, as seen by their aggressive and independent nature.
Nidorino may be a combination of needle and rhinoceros. Nido may also be based on cnidocyte, a type of venomous cell responsible for the stings delivered by stinging animals, most notably by jellyfish. Alternatively, it may be based on 二 ni (two) or 二度 nido (two times/two degrees), referring to the two distinct evolutionary lines using the name with similar names and traits. Rino likely alludes to its male gender; in some languages, such as Spanish, names and words ending in o are an indication to the male gender.