"Young Justice Halloween Party" from Young Justice #3 (1998) by Peter David, Todd Nauck and Lary Stucker
When the Titans grew up, or were replaced by no-names or whatever was happening in that book, the real sidekicks and higher-end super teens could be found in Young Justice. A whole lot of fun the Titans stuff should have aspired to! Sadly, many of these guys would wind up in a Titans book eventually. Bad move.