Pokémon G/S Walkthrough - Chapter 23

Pewter City

Pewter City Gym - Brock

Brock still uses Rock Pokémon but just to make it a little more interesting he has added a few Rock/Water combinations for you to struggle with. But don't worry, Hydro Pump can still take them out with no problem. If not, a good Grass attack should do nicely. And for the other Pokémon: Water attacks. Brock will give you his Boulder Badge after you defeat him which will make your Pokémon even stronger. Now head East towards Mt. Moon.

Brock
Pokémon	Level	Exp.
Graveler	41	1176
Rhyhorn	41	1185
Omastar	42	1791
Onix	44	1017
Kabutops	42	1809
Prize: $4200

Rainbow or Silver Wing

Depending on which version you're playing, talk to this old guy in Pewter City before you leave. He'll give you the Silver Wing (in Gold) which will allow you to catch Lugia. Or the Rainbow Wing (in Silver) which will allow you to catch Ho-oh.