Create category pages for network wide posts

Hi,

I'd like to have custom_category pages on my main site that include custom posts from across my network in the individual categories. Do I need to create a custom page template for this? If yes, what code do I need to include?

The custom_categories are all synced across the network using the Multisite Global Terms plugin.

I have got custom tags working using an adapted version of the Global Site Tags plugin.

Thanks for your help.
Alex