A great system team is a truly cross functional team with representation from core infra, development, testautomation, devops tooling, monitoring and plattform experts. A great system team has a product owner that is peer with other product owners so that activities are planned in collaboration between products and ART capabilities. A great system team have some members that are supportive and service minded and some that are capable of building complex solutions like different deployment strategies, integration test automation, automatic release note generation.
A great system team is able to balance between standardisation for the benefit of the whole and variability for local requirements and innovation. The former is the hardest. Having agile team comply with standards and restrains requires authority. The system team need members who naturally has such authority.