How do you get past the second lock on third gym of Pokemon fire red?

You get past the second lock on the third gym (the Rock Gym in Vermilion City) by using a Pokémon that can learn the move Strength.

Here's how:

1. Find a Pokémon that can learn Strength: Some common Pokémon that can learn Strength at this point in the game are Machop, Mankey, and Geodude. You can find these Pokémon in the following locations:

* Machop: Route 4, Route 24, Victory Road

* Mankey: Route 5, Route 24

* Geodude: Route 4, Route 24, Victory Road

2. Level up your Pokémon: Make sure your chosen Pokémon is high enough level to learn Strength. The move can be learned at level 15 for Machop, level 17 for Mankey, and level 18 for Geodude.

3. Teach your Pokémon Strength: Head to the move tutor in Celadon City (the department store) and teach the move Strength to your Pokémon.

4. Use Strength to move the boulder: Once you have Strength, return to the second lock in the gym. Use Strength on the boulder blocking the path and it will be moved, allowing you to progress through the gym.

Tip: After you learn Strength, you can also use it to clear the way to the third gym's main entrance, which is blocked by a boulder outside.

Remember that gym leaders usually have Pokémon that are strong against the type you're using, so try to be prepared for a fight.