Rhyhorn is a rhinoceros-like Pokémon with a body covered in gray, rocky plates. Its underside and rear are smooth, and it has four short legs with two claws on each foot. It has a triangular head with narrow, red eyes, two fangs protruding from its upper jaw, small, triangular openings on the upper sides, and a short horn on the tip of its snout. A female will have a shorter horn than a male. A spiked ridge runs along its back. In addition to its rocky hide, its bones are a thousand times harder than human bones.
Rhyhorn's brain is very small, giving it a one-track mind. When it runs, it forgets why it started and continues until it falls asleep. However, it may recall the reason upon demolishing something. Due to its short legs, it is inept at turning and can only run in straight lines. It does not care if obstacles get in the way, merely smashing through them or sending them flying, although it may feel pain the day after a collision. Rhyhorn is powerful enough to shatter skyscraper or mountains instantly after charging forward with head tackles. Rhyhorn lives in rough terrain.
In Bulbasaur's Mysterious Garden, a Hiker used a Rhyhorn in a battle against Ash's Bulbasaur, which it lost.
In Mewtwo Strikes Back and its remake Mewtwo Strikes Back—Evolution, Corey's Rhyhorn was captured and cloned by Mewtwo. By Mewtwo Returns, the Rhyhorn clone had bred a baby Rhyhorn with the clone of Fergus's Nidoqueen.
In In the Pink, a pink Rhyhorn was the first Pokémon that Ash and his friends saw at Pinkan Island. Although it was initially unaware of the trio, Ash rushed up to it and antagonized it. It then cornered the gang at the edge of a cliff and attempted to charge at them, but the group was saved by Togepi using Teleport via Metronome, causing Rhyhorn to charge over the cliff. It was then rescued by Ash and his friends with the help of the resident Officer Jenny.
In Odd Pokémon Out!, multiple Rhyhorn living on Camomile Island charged at Ash's Donphan, believing it was threatening their children when in fact it was only trying to play with them.
Grace's Rhyhorn first appeared in Kalos, Where Dreams and Adventures Begin!, having been a pet since retiring from Rhyhorn Racing. In the episode, Serena tried Rhyhorn training before she left home. Rhyhorn has since made further appearances in Pokémon the Series: XY.
In Giving Chase at the Rhyhorn Race!, multiple Rhyhorn were entered in a Rhyhorn race, including Ian's. The Rhyhorn were targeted by Team Rocket but ultimately rescued by Ash and his friends.
In Diancie and the Cocoon of Destruction, Serena, Clemont, Bonnie, and Diancie borrowed a Rhyhorn from the Orsay City Rhyhorn racing track in order to escape from Merilyn and Riot. After the group got to safety, Serena thanked Rhyhorn for its help and it went back to the racing track.
In A Race for Home!, Serena hijacked a Rhyhorn to chase Team Rocket when they stole a supply of cheese.
In Master Class Choices!, multiple Rhyhorn were used as part of the Theme Performance of the Fleurrh City Pokémon Showcase. The Performers had to attract the most Rhyhorn in a certain period of time. Serena found that most of the Rhyhorn were attracted to her, allowing her to advance to the next performance.
Rhyhorn debuted in The Flame Pokémon-athon!, where many of them were at the Laramie Ranch. One was later seen among the Pokémon participating in the Big P Pokémon Race. Rhyhorn jumped onto a stone with its Trainer, but they sank due to Rhyhorn's weight and were eliminated from the race.
In the banned episode EP035, Ash attempted to catch a Rhyhorn in the Safari Zone, but it got away. A flashback featured another Rhyhorn.
In A Chansey Operation, an injured Rhyhorn was brought to the clinic.
In Showdown at the Po-ké Corral, multiple Rhyhorn were living at Professor Oak's Laboratory. They reappeared in A Tent Situation and The Rivalry Revival.
In The Power of One, a Rhyhorn sensed the disturbance caused by Lawrence III.
In Tricks of the Trade, a Rhyhorn was at the Pokémon Swap Meet in Palmpona.
A Rhyhorn appeared in The Legend of Thunder!.
Multiple Rhyhorn appeared in Celebi: The Voice of the Forest and Pokémon Heroes: Latios & Latias.
In Johto Photo Finish, Jon Dickson's Rhyhorn defeated Harrison's Houndoom, thus clinching Jon's place in the Silver Conference finals.
Multiple Rhyhorn appeared in Destiny Deoxys.
In Beg, Burrow and Steal, a Rhyhorn was living in an underground paradise.
In Numero Uno Articuno, a Rhyhorn was living at the Battle Factory.
In Lucario and the Mystery of Mew, multiple Rhyhorn were part of the feuding armies that were eventually placated by Sir Aaron in the past.
A Coordinator's Rhyhorn appeared in Harley Rides Again.
A Coordinator's Rhyhorn appeared in May, We Harley Drew'd Ya!.
In Pokémon Ranger and the Kidnapped Riolu! (Part 2), J's client's henchmen used a Rhyhorn to attack Dawn, Brock, Officer Jenny, and Solana.
A Rhyhorn appeared in Camping It Up!.
In Pokémon Ranger: Guardian Signs (Part 1), several Rhyhorn were captured by the Pokémon Pinchers.
A Rhyhorn appeared in the opening sequence of Giratina and the Sky Warrior.
A Rhyhorn appeared in the opening sequence of Zoroark: Master of Illusions.
Multiple Rhyhorn appeared in a flashback in A Showcase Debut!.
In I Choose You!, a Rhyhorn fell under the control of Marshadow.
Three Rhyhorn appeared in Legend? Go! Friends? Go!.
Two Rhyhorn appeared in JN136.
||Rhyhorn, the Spikes Pokémon. It's covered in a tough armor, giving its Tackle attack an extraordinarily destructive power.
||Rhyhorn, the Spiked Pokémon. Rhyhorn is known for its physical power and its considerable offensive and defensive battle skills.
||Rhyhorn, the Spikes Pokémon. Rhyhorn recklessly charges straight ahead, trampling over anything that gets in its way.
In File 3: Giovanni, Giovanni used a Rhyhorn during his Gym battle against Red. It took out most of his team and tied against his Hitmonlee.
A Trainer's Rhyhorn appeared in Blossom's Dream where it helped protect a village from a Nidoking and Nidoqueen.
The Electric Tale of Pikachu
Drake's Rhyhorn was only seen in a flashback. It is currently unknown whether or not he still has it.
A Rhyhorn appeared in Celebi: a Timeless Encounter. It was only seen in a Pokémon hunter's camp.
Pocket Monsters HGSS
A Rhyhorn appeared in PMHGSS04.
A Rhyhorn appeared in PMHGSS11.
Rhyhorn debuts in Raging Rhydon, under the ownership of Koga. After getting defeated by Red's Pikachu, Pika, it was forced to evolve with a mysterious injection, and knocks out Misty with its increased power.
In Long Live the Nidoqueen!?, a Rhyhorn is seen in possession of Giovanni. It is one of his main fighters, who knocked out Red's Aerodactyl with a simple Tail Whip. He also later uses him in the battle with Lance to generate a sandstorm by crushing rocks.
A Rhyhorn appeared in The Last Battle XIII as one of the Pokémon sent to participate in the fight in Ilex Forest.
In Interesting Interactions Involving Illumise, Rhyhorn was one of the rental Pokémon used by Emerald in his Battle Factory challenge.
The Battle Factory rented a Rhyhorn, which was stolen by Guile Hideout in Skirting Around Surskit I.
The Battle Factory rented a Rhyhorn, which was stolen by Guile Hideout in Lemme at 'Em, Lapras!.
A Rhyhorn belonging to Y debuted in An X-cuse to Come Out and Play. He was originally owned by Grace. He often carries X around while he sits inside a tent attached to his back. Much later, Y decides to officially keep Rhyhorn on her team and nicknames him Rhyrhy.
Multiple Rhyhorn appeared in Shooting Frogadier.
A Rhyhorn appeared in Gathering Klefki, under the ownership of a Rhyhorn racer.
Shigeru has a Rhyhorn, which he caught in the Safari Zone.