Its horn is harder than a diamond. 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.
(From Bulbapedia)Nidorino is a light purple, quadruped Pokémon. It has several darker purple spots 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. It 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. This is a male only species; the female counterpart is Nidorina.
Nidorino is independent and fierce, 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 live in hot savannas and plains.
(From Bulbapedia) Nidorino appears to be based on a rhinoceros, porcupine, rabbit, mouse, or even a hamster, as seen by their aggressive and independent nature.
(From Bulbapedia)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.