Brock's Geodude (Japanese: タケシのイシツブテ Takeshi's Isitsubute) was the second Pokémon acquired by Brock in the anime; Brock has a Geodude in most of the games he appears in, as well.
Geodude was first seen in Brock's rematch with Ash at the Pewter City Gym. Initially, it was used against Pidgeotto; it was unfazed by Pidgeotto's Gust, demonstrating its strong defense, and as a result it was able to defeat Pidgeotto without any trouble. It was then used against Pikachu, but was fried by a very powerful Thunderbolt, despite the fact that it is immune to Electric moves.
Like most of Brock's Pokémon, Geodude received very little screentime. Brock typically used Geodude in situations in which Brock needed to battle, but could not use Onix because of its enormous size. One such occasion was Battle Aboard the St. Anne, when Brock's Geodude joined a larger group of Geodude attacking Team Rocket.
Geodude helped fight the fire in Celadon Gym in Pokémon Scent-sation!, by smothering the flames with dirt. In Pokémon Fashion Flash, it was revealed to know Seismic Toss by throwing Jessie's Ekans. However, it was blinded by Koffing's Sludge.
Brock entered Geodude in the P1 Grand Prix in The Punchy Pokémon. It lost in the first round to Giant's Hitmonlee which was used by Team Rocket. Initially, Brock sent Geodude back into the ring where it was kicked mercilessly, but on Anthony's advice, Brock threw in the towel and apologized to Geodude for making it fight.
Geodude also dug a hole to rescue Ash and Pikachu in Attack of the Prehistoric Pokémon. However, before the pair could be pulled to safety, Aerodactyl broke through the hole and held Ash captive. Geodude also displayed the first use of its Tackle attack while breaching Team Rocket's house with Ash, Pidgeotto, Misty and Staryu.
Geodude's advantage over fire was once again demonstrated by helping Onix, Charizard and Blaine's Magmar dam the erupting Cinnabar volcano in Volcanic Panic. It was kept cool by the efforts of Squirtle and Staryu.
Geodude made another appearance in Pallet Party Panic.
Geodude accompanied Brock to the Orange Islands. In A Scare in the Air, during battle with Team Rocket, it hurled Weezing through the side of a blimp, causing severe damage and forcing the blimp to crash-land on Valencia Island. In the following episode, Poké Ball Peril, Geodude stayed with Brock at Professor Ivy's lab.
Brock, Geodude, and Brock's fellow Pokémon returned in A Tents Situation. In Sick Daze, it was revealed that Brock usually polished his Rock Pokémon, so Misty took up the job of polishing Geodude while Brock was sick. Geodude was captured by Team Rocket, but was rescued when Brock, Pineco and Golbat intervened.
In Control Freak!, Geodude dug a pathway to get into the ancient ruins. However, once inside, Jessie, in possession of the ancient Queen's mask and scepter, took control of Geodude, along with Onix and Pikachu. However, once Jessie, James and Meowth escaped with Pikachu on Onix, Geodude was left behind and snapped free of Jessie's control.
Geodude was also used in EP250 (an unaired episode in the dub) where it fought Jessie's Arbok, but was easily defeated by Arbok's Headbutt and Wrap. It was then stolen by Team Rocket, but recovered later. Geodude acted as a fire fighter for the third time in Great Bowls of Fire!, where it attempted to rescue the Pokémon trapped in a fire. It managed to save the sacred Prayer Flame from the burning shrine at the end of the episode. In Entei At Your Own Risk!, Geodude was sent out to enjoy the hot sands. It pushed Ash's Larvitar headfirst into the hot sand, showing no patience for Larvitar's timidity.
In the Christmas special, Geodude was seen helping Delibird retrieve its presents. Geodude was also seen having a snowball fight with the rest of the Pokémon in Kanga Games.
Brock lent Geodude and two of his other Pokémon to his younger brother, Forrest, who took on the role of Gym Leader of the Pewter Gym when Brock went to Hoenn in The Family That Battles Together, Stays Together.
Kanto Battle Frontier
Geodude joined Crobat and Steelix to greet Brock in Grating Spaces!. Forrest ordered Geodude to Tackle Meowth, and then it used its newly learned Sandstorm to create a distraction whilst Steelix created defenses with boulders. It then charged and took down Jessie's Charizard with a Mega Punch.