Several months ago there was a sign outside a middle school near where I live which read,
Congratulations to the promoting class of 2009!
I was familiar with the use of promote as something a school does to a student advancing to the next grade, and the particular significance of being promoted from middle to high school. But the syntactic contexts for this were school promotes student or promotion of student, etc., roughly transitive uses. This contrasted in my usage with graduate, where a student may graduate or a school may graduate a student. So, for me, graduating class was perfectly normal, while promoting class was out. But it seems to be not all that rare, and after all, why not? If it’s to be used pretty much parallel to graduate, why not let it take syntactic positions more like the latter?
But still, would you expect to find it as a main rather than in the -ing form? From here:
6th grade students who have promoted in 2008 will attend a middle school campus and 8th grade students who have promoted will be assigned to a high school site.
So far I’ve found only one such thing.
Then, there’s also advance. Students and classes advance to the next grade, and there are advancement ceremonies. But would anyone congratulate the advancing class of 2009?