Obviously this is about Zod, and which stories Happened. In Action Comics 981 Zod says to Superman "it's been too long" and "your reflexes have gotten slow. Lazy." This indicates that they have fought before, but which story. The only stories I can think of is altered versions of last son or the Superman/Wonder woman story. Maybe at the end of last son, Chris Kent decided to embrace his father's ideals and hated Superman. Or is it a altered Superman/Wonder Woman where they aren't dating and faora is Ursa. Or maybe there is a story they need to write to show us the first meeting between Superman and Zod.