Are oharah and meet du together in the actual game?
Or are they just "good friends" that the fans like to ship?
Er... By "oharah" and "meet du" I assume you mean Pharah and Mercy (phone autocorrect error I presume..?). They're not "together" in any official sense but Mercy's ability to fly to an ally and hover in the air combined with Pharah's jump jets and boosters synergize well.
Oh God for some reason this site and my auto correct don't get along at all. I've gotten so lazy to the point where when I see that the text got auto corrected I don't even proofread anymore. Gotta work on that.