Pokémon FireRed and LeafGreen/Pewter City

'In Pewter City, you will fight Brock, your first Pokémon Gym Leader. The Pokémon he uses in battle are strong. If necessary, build up the experience of your own Pokémon by having battles in the wild. Before you do either, visit the Pokémon Center in Pewter City, so if your Pokémon faint in battle, you'll resume your journey there, instead of far away.'

You can't leave
If you try to leave town to the East, you'll be sent to deal with the town's trainer, Brock, at the Gym in the middle of town, below the Museum. Until you've bested him, you're stuck here.

The Science Museum
It'll cost you 50 to get into the Museum (the large building in the North part of town), and while there's lots of interesting exhibits, nothing here will help you directly. The good stuff is in the back, but that way is blocked by one of those annoying plants... You'll have to come back later.

Once you do have Cut, you'll get the old amber from a scientist who is interested in extracting Pokemon DNA and will ask you to take it to a research institution.

Battles
Brock and his Junior Trainer use Rock- and Ground-type Pokémon, which are weak to Grass and Water. If you picked or  to start, you should have an easy time of it, but if you picked, you will have problems. There are several ways to defeat Brock without Squirtle or Bulbasaur:


 * Level Charmander up so it can win the fight through superior strength. At level 13 it will learn Metal Claw, a Steel-type move, which is super effective against Rock-types. Note that Rock-type attacks are super effective against Fire-type Pokémon so make sure you're stocked up on potions first. Critical hits can happen any time, so heal often!
 * Rock-type Pokémon are also weak against Fighting-type, so using isn't bad idea. It learns Low Kick move at level 6. Mankeys can be found on route 22.
 * Catch a Caterpie at Viridian Forest and evolve it to Butterfree. When evolved to Butterfree, it learns Confusion, a Psychic-type attack. Though it isn't super effective against Rock, it still does major damage since Geodude's and Onix's Special Defense stats are very low. Note that Butterfree (being (Bug/Flying type) is very weak against Rock attacks.

If you defeat Brock, he'll give you TM 39 (The Rock Tomb attack technique) and his Boulder Badge, which grants your Pokémon a small power boost and allows you to use Flash (once you have HM 05). Additionally, you will get a TM/HM Case, which allows you to store your TMs and HMs without occupying any more space in your gear bag.

Items

 * Poké Ball (top left corner of the city in the light grass)
 * TM 39 - Rock Tomb (Brock after you defeat him)
 * Running Shoes (on the way to route 3 after you defeat Brock)