Have everyone in the raid load this.
This is a rewrite of 2 other addons, it basically adds sync functionality for the Raid Leader, so the entire raid doesn't have to reload this weakaura every raid.
The raid leader can setup groups in Custom Options.
Once encounter starts, this will sync to the entire raid over addon msgs.
If someone wants to know groups beforehand type !groups in raid, and the raid leader will broadcast the groups in raid chat.
Thankyou to these 2 other weakauras that I stole most of this code from.