The styles are pretty different, but I think we are all trained to watch the leader and do well with each other's moves as long as we don't get into super long combos...
If you've ever seen groups get together and do the now traditional Tribal Union (started by Ayse & Brandy a few years back) to end a tribal festival you would see how it works to have people of many troupes dancing improv together....it's so fun!!!

I'm not a dancer, just married to one.. Kajira who's BlackSheep ATS you mentioned.... I know at Tribal Fest, when we have open floors and everyone comes together,,, they pull it off,,, sometimes you see them in little groups, but it seems that the basic moves are all pretty close... FCBD... that is the foundation of ATS, I think as I understand it..

So when open floors come up,,, it seems like the leader doesn't throw in to many "troupe specific" moves...

They are there to have fun and it is a very casual deal,,, dancers dancing and sharing the love of the dance..

It realy depends.But once a few members of unmata danced with Rachel Brice and some others who mostly did fatchance ATS and it whent okay in the end most styles have an Egyptian halfturn and a choochoo.Not everyone is going to know the Happy Birthday Grapevine but most ITS still follows basic ATS ideas.