It is related to the Nidoran♂ line, but unlike Nidoran♀, Nidoqueen cannot breed.
Nidoqueen is a large, bipedal blue Pokémon with distinct reptilian features. Its body is encased with extremely hard scales that serve as excellent protection from any attack and stand up when Nidoqueen is excited or provoked. It has a blunt snout, narrow brown eyes, and large ears with brown insides. There is a small horn on its forehead, and single spine on each ear, and there is a line of toxic spikes running down the length of its back. Each hand has three short claws and each foot was two claws. Its lower jaw, the front of its abdomen, and two plates on its chest are cream-colored. It has a thick, powerful tail.
Nidoqueen can be quite fierce and is very protective over its young. This Pokémon is at its strongest when it is defending its young, and will try to seal the entrance to its burrow to protect them. When in contact with foes, it can poison them with the spikes from its back or cause small tremors by slamming the ground. It is also adept at sending foes flying with harsh tackles and it uses its hefty bulk to execute powerful moves. Nidoqueen lives in hot savannas and plains.
Nidoqueen debuted in Mewtwo Strikes Back, under the ownership of Fergus. She was one of the Pokémon that were captured and cloned by Mewtwo. The Nidoqueen clone was seen again in Mewtwo Returns, along with what was apparently a Nidoqueen baby, despite the fact that Nidoqueen cannot breed and her unevolved form is Nidoran♀.
A Nidoqueen appeared in The Bicker the Better, under the ownership of Andi. Her boyfriend Oscar had a Nidoking. They had a Double Battle with Ash and May, and due to Oscar and Andi's communication with each other, they were able to defeat Ash and May with relative ease.
Four Nidoqueen appeared in Arceus and the Jewel of Life, under the ownership of Damos. In the original timeline set up by the movie, they were used by Damos, who was under Hypnosis, to attack Arceus with Shock Wave. When Ash and his friends traveled to the past to prevent this, Marcus, the one responsible for hypnotizing Damos, managed to use the Nidoqueen again to attack Arceus.
Aside from Nidoking, no other Pokémon has the same typecombination as Nidoqueen.
In the Japanese games Pokémon Red and Green, Nidoqueen weighs 6.0 kg instead of 60.0 kg (as it does in all other games). This has no mechanical significance, as no game mechanics use weight in the handheld Generation I games.
Prior to Generation IV, Nidoqueen was depicted in the games and official artwork as having fangs. Why her fangs were removed in later generations is unknown.
Nidoqueen may be a combination of needle and queen (reflective of its gender and being the final evolution). 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 there being two distinct evolutionary lines using the name with similar names and traits.