Pokémon FireRed and LeafGreen/Rock Tunnel

The Rock Tunnel Connects Route 10 to Lavender Town. To get through, you need to have a Pokémon that knows the HM05 Flash. There is also a Move Teacher who will offer to teach Rock Slide to one of your Pokémon on the second floor.

If you picked Squirtle or Bulbasaur as your starter and leveled it up decently, you'll have little problem getting through. Those who picked Charmander as their starter will struggle though, as the rock types here are super effective against fire types. Pick up as many super potions as you can in Vermillion City, as you'll be using them. Worry about getting to the other side and come back for the items/Pokemon later once you have a stronger team.

On the second level, in southwest corner, there is a guy who will teach your Pokémon Rock Slide.

Items

 * Max Ether
 * Revive
 * Escape Rope
 * Pearl
 * Repel
 * Super Potion