Pewter Gym

Pewter City Gym (Japanese: ニビジム Nibi Gym) is the second gym in the game, but the first gym battled. The Gym Leader, Brock, specializes in rock-types.

In the Anime
In the anime, Ash faced off against Brock by using Pidgeotto and Pikachu. The first time they fought, Ash had lost. However, the second time, the battle was left undecided. Still, Ash earned his first Badge, the Boulder Badge.

When Ash fought Brock, Brock used Onix and Geodude to defeat Ash's Pokémon with ease. Soon after, a strange man, namely Brock's father, Flint, gave Pikachu a power-up which allowed Pikachu to overcome type advantages and immunities to defeat Brock's Geodude. However, Ash felt as if Pikachu had cheated when Brock use Onix because Pikachu set off the sprinkler system in the Gym. This hurt Onix and allowed Pikachu to use electric attacks more effectively against the ground-type. Before the final blow, Brock's siblings held Ash back, and Ash threw the match.

Pokémon
This is a list of Pokémon Brock used to fight against Ash and their attacks.