Brock, also known as Takeshi in Japan, has always wanted to be a great Pokémon breeder. Although he maintained the title of Gym Leader, Brock Takeshi leaves it all behind to travel with Ash Ketchum and Misty on their journey.
The funny thing about Brock is that he seems to fall for almost every single girl that he meets. He can't help but make flirtatious advances at them and it usually ends up in total rejection and embarassment.
Brock has always had many Pokémon of his own. Most of which are ground-type and rock-type. But, as a Pokémon breeder he is used to training many other types as well. Among his long list of Pokémon you'll find Bonsly, Croagunk, Happiny, Onix and Geodude to name a few.