I don't have my GameShark with me, but here's how you would find such a code.
You see a code like this:
- Giovanni (Silph Co.)
And you figure that the rest of the Silph Co codes will be around 01??37D8.
You plug in all these codes:
and find that this resets all of Silph Co as well as some other parts of the game. With a bit of experimentation you can find which of these codes are actually necessary for just Silph Co.