Instructions
Head to the southeast corner of the Ironworks, then veer north. When you come across two direction pads, take the left one. This will shoot you toward your first opponent, Worker Dillan.
Speak with Worker Dillan to initiate the battle. By the time you reach the Ironworks, your pokemon will outclass Dillan's pokemon by a margin of several levels. To improve your odds of success, use psychic or ghost pokemon.
Walk southeast and then take the lower direction pad. This shoots you east and then north, where you'll find your second opponent, Worker Holden. Pit a water or fire pokemon against him to take Holden out quickly.
Go north to face off against Worker Conrad. Use a water or rock pokemon to decimate his Ponyta.
Take the left direction pad to arrive at Mr. Fuego's office. Speak with him, and he'll give you a Fire Stone.