Let's assume Atlantis is on land. Everything /vehicle/ that was shown in the Aquaman movie is now assumed capable of "flying" as well as it could perform underwater. Arthur is King but has Orm with him.
Wakanda has its shields raised at the start of the match. Panther is King but they get Kilmonger as well.
The two nations are 50 miles away from one another. Small hills and forest between them with some open fields here and there.