If your application is part of a Multi-Event Application, which is the case for most of our clients, you will not need to submit an additional graphic here unless you would like to update your previously submitted store graphics. If this is a stand-alone app, the Apple Watch Graphic is required in order to be displayed in the App Store for the event's app. Black or dark background graphics are not accepted for the Apple Watch Graphic.
Note that anything that requires app store updates will require coordinating with your Core-apps liaison.