I developed a Chrono Trigger ATB system, though it is only about 85-90% percent finished. I don't have the time at the moment to finish it, but I would offer to this project as either a script to get ideas from, or even if someone wanted to attempt to finish it for me.
It has way too many feature to list here, but it basicacally just think of CT's system, where you have a caterpillar, but when battle is initialized, each character runs to there place and combat begins on the map. The biggest thing that needs done on it is to finish how stances work during different commands, but a combo system for dual and triple attacks is already implemented, and high comaptibility with almost every script in Tons and other popular scripts has been maintained.