Which assets cannot be shared in the Solutions Gallery?
- Custom reports
- Custom Dimensions
You can share Dashboards, Custom Reports, Segments, Goals, and Custom Attribution Models in the Solutions Gallery. Only configuration data is shared through the Solutions Gallery. When you create and share an asset, your personal information and Analytics data stays private in your account. And when you import an asset from the Solutions Gallery, only the template is imported into your account.
Read more here: https://support.google.com/analytics/answer/3314024