Brock is the leader of Pewter City gym in Gen 1 (Pokemon Red), Gen 2 (Pokemon Crystal), Generation 3.5 (Randomized FireRed), Gen 4.5 (Randomized HeartGold) and Anniversary Red. He serves at the first gym leader faced in the Kanto region generation games.

It is believed that he follows the Old Amber, as his stronger teams contain both Omastar and Kabutops, and in the Anniversary run this also included Aerodactyl, completing the trio of Fossil Pokémon, while his rematch team included all three.

Teams[]

Original Red[]

Versus Brock

Level	Pokemon Name	Type	Moves
12	Geodude	Rock/Ground	Tackle, Defense Curl
14	Onix	Rock/Ground	Tackle, Screech, Bide, Bind

Crystal[]

Versus Brock

Level	Pokemon Name	Type	Moves
41	Graveler	Rock/Ground	Defense Curl, Rock Slide, Rollout, Earthquake
41	Rhyhorn	Ground/Rock	Fury Attack, Scary Face, Earthquake, Horn Drill
42	Omastar	Rock/Water	Bite, Surf, Protect, Spike Cannon
42	Kabutops	Rock/Water	Slash, Surf, Endure, Giga Drain
44	Onix	Rock/Ground	Bind, Rock Slide, Bide, Sandstorm

Randomized Fire Red[]

Versus Brock

Level	Pokemon Name	Type	Moves
12	Venonat	Bug/Poison	Poisonpowder, Megahorn†
14	Ledian	Bug/Flying	Megahorn†

Randomized Heart Gold[]

Versus Brock

Level	Pokemon Name	Type	Moves
51	Sealeo	Ice/Water	???†
51	Delibird	Ice/Flying	???†
53	Glalie	Ice	???†
52	Mamoswine	Ice/Ground	???†
54	Sealeo	Ice/Water	???†

Anniversary Red[]

Versus Brock

Level	Pokemon Name	Type	Moves
15	Onix	Rock/Ground	Bind, Screech, Tackle
17	Aerodactyl	Rock/Flying	Rock Slide, Wing Attack, Agility

Rematch[]

Versus Brock

Level	Pokemon Name	Type	Move
100	Onix	Rock/Ground	TBA
100	Rhydon	Ground/Rock	TBA
100	Golem	Rock/Ground	TBA
100	Omastar	Rock/Water	TBA
100	Kabutops	Rock/Water	TBA
100	Aerodactyl	Rock/Flying	TBA