1. From a Trainer:
* Route 43: You can get one from a Trainer named Jeremy after you defeat him.
* Route 48: You can get one from a Trainer named Ben after you defeat him.
2. Finding it in the Wild:
* Route 46: You can find a Fire Stone in the tall grass here, but it is rare.
3. Using the "Berry Master" Trick:
* Berry Master (Goldenrod City): You can trade certain berries with the Berry Master for stones.
* Required Berries:
* For a Fire Stone, you'll need to trade a Razz Berry.
Important Note:
* The Fire Stone is a relatively common item in SoulSilver. If you're having trouble finding one, keep exploring and challenging Trainers in the areas mentioned above.
Let me know if you have any other questions!