I’m working on making a Fighting Game template, and I am using Substance Source materials. Can I legally post a template on the marketplace that uses this?
If you obtained the substances via the Substance in Unreal Engine plugin from the Marketplace, you are not permitted to distribute such content in uncooked source format (in the Marketplace or otherwise). If you obtained those substances directly from Substance, your use and distribution rights will depend on your license from Substance.