Dream character team up.
Batgirls from Batgirl #24. This was part of a dream sequence (See? It fits on that level too!) for the final issue of the Bryan Q. Miller run, and it could have been a story he told if DC hadn’t relaunched and put Barbara Gordon back in the suit.
Or, Batgirls from All-New Batman: The Brave and the Bold #13. I’m not cheating by presenting two options because it’s still a Batgirl team-up. :) Here, if the Robins throughout time had failed in their mission to save Batman, Madame Xanadu was poised to send in the Batgirls from across time to save the Bat’s butt. If I wasn’t such a Robin fan, I would have preferred this story.