It's definitely confirmed: was in Corocoro, and I (sorta) translated the scan myself on top of what was already reported. I can make out that it's saying something along the lines of "Legendary Pokémon in the 2010 World Championships!" with some more stuff that I couldn't really see. I'm only just getting used to hiragana and I'm basically clueless when it comes to the actual language other than the kanji for "legendary" so yeah.
This is in addition to the Sunday stuff as well. It's a shame I guess, however it makes it easier to weed out the weaker players. With ubers you're not going to be losing to noobs any time soon, whereas if you used a setup team it's actually possible to get extremely unlucky and lose to a numbnuts 10-year-old. Not that I did lose to said numbnuts 10-year-old; I lost to UltimateUnknown who won the tournament, but still. It's better to be safe than to suffer a humiliating loss: Murphy's Law prevails, after all.
And something else: Maybe there won't be the lvl50 limit this time? While it'd make sense with the new lvl50 legends, isn't the idea for little kids to use their favourites? And isn't it obvious that little kids' favourite pokémon will have been trained to lvl100? Everyone including kids will have to get new ubers for the tournament, so this move doesn't make all too much sense if they keep it lvl50.