I believe Triple and Rotation battles are available if the trainer requests it, such as Flame requesting double battles in her training thread, as an actual example, and can be used. Exp would just be divided amongst the three as per usual. It's also up to the Mod to make one happen if it isn't requested, just like any other kind of battle.
We did talk about props for contests, but it was decided against for the sake of keeping things easy and smooth. Perhaps if you wanted them and came up with a system for using them, it could be considered to be added. As of currently, I don't know of any members entering Musicals, so I don't have a reply for that except that it could use a similar system if it is introduced.
As for X and Y, yes, things will be added. But not until after the games' release.