While it's tempting to try to find more Master Balls, the game is designed in a way that you only ever get the one. This is to ensure a balanced challenge and prevent players from overpowering the game too easily.
Here are some alternative ways to catch Pokemon in Pokemon Soul Silver:
* Use other Poke Balls: There are plenty of other great Poke Balls available throughout the game, each with different catch rates.
* Utilize status conditions: Paralyzing, freezing, or putting a Pokemon to sleep can significantly increase your chances of catching it.
* Lower the Pokemon's HP: A Pokemon with low HP is much easier to capture.
* Use berries: Berries like Razz Berries can increase your catch rate.
* Level up your Trainer: A higher level trainer has a better chance of catching Pokemon.
Ultimately, you'll have to rely on your skills and strategy to catch the Pokemon you want without relying on the Master Ball!