How do you get to the Omanyte puzzle in Ruins of Alph Pokemon gold?

You can't get to the Omanyte puzzle in Pokemon Gold.

The Omanyte puzzle is exclusive to Pokemon Silver, found in the Ruins of Alph in the Ilex Forest.

In Pokemon Gold, the Ruins of Alph contain a different puzzle involving a Sudowoodo statue and the need to push rocks into certain positions.

Are you perhaps thinking about the wrong game? 😊