Anyone who is in one of the participating countries and apparently excluded from All Stars for any reason (such as being banned or having too much gold or boosters conferring an "unfair advantage") should seriously consider starting a brand new account this weekend and hopefully participating in the second qualifier round that starts on Monday with it. Make sure the app cannot trace who you are, so choose a different device if you can or download the app afresh. (As always, of course: Do not uninstall the app if you have any boosters as those will be lost)
Here is why I think new players are being favoured in the qualifiers:
This is my leaderboard after 18 hours play. I started the account about a week ago and reached level 200 by the start of the tournament. Of those other players you see three have actually used some multiplier tokens! None of them have played more than one episode.
The first 200 levels remain pretty grim, but once you get past level 200 it's really easy to make lots of gold. I think there is a real opportunity here for anyone to crush away at the pre level 1000 range and make enough gold to use later on in the competition. You would have to play a lot of Candy Crush during the qualifier round, to make as much gold as you can, so don't join late but quite to the contrary: Join as early as you can so you can make more gold along the way to use in the final knockouts. It's possible to make a few thousand gold by level 1500.
Don't wait for the second chance rounds. I doubt you would receive six tokens in those, and there would not be enough time to earn a lot of gold before the going gets tough.
As always this comes with no guarantee, it's just a hunch I have from my experience with the game and all the testing I've done over the past 12 months.
Good luck!