Actually, Garchomp was allowed even before VGC 2010 and since the info release about two "UBERS" per team, Garchomp usage has gone down quite a bit (at least in Japan and Korea not too sure about other countries...since I havent been to anywhere but the two sorry).
Lugias...meh its one of the least used UBERS thats been allowed this year due to the lack of raw power. Defense is good but the double battling...really doesnt tolerate stall or stalling pokemons too well lol.
Palkias are one of the most used (probably top 3). However, I have never seen a scarfed palkia as of now. 99.99% go with the following moveset: spacial rend, surf or hydro pump, thunder or fire blast (thunder is more used), protect.
Scarf...its used in the double battling meta but it is rarely seen as choice items tend to be HORRIBLE in this metagame.
Garchomp is a beast in Ubers from what I've seen, so I would predict huge usage of it (but then again, I'm just making educated guesses, I haven't studied yet). There may be lots of Scarves, but I also think we'll be seeing a lot less Exploders. Lugia, I guess wouldn't do very well, but I was just pulling things off the list that had nice stats.
Whatever goes down, this will certainly be interesting.
Well aware of that. I was hoping you could infer that from my post.Umm, no - there is no chance.