So Really how? you can't just walk up to the tournament and say umm.. yea i'm in group D, A, or watever you want.
usually, tournament style is drop then semi-elimination. everyone 'starts' in the A category. If you win your first two sets, you are A. If you Win-Lose, you are B, if you Lose-Win, you are C, and if you Lose-Lose, you are D. After the first two games, you compete until you are eliminated, i think. I know in some tourneys, you can drop from B to C if you lose to a third team.
I've actually only played that style in Washington. In California, you choose your flight and there's no dropping unless you drop into cons after losing your first match. If you lose again, then you're completely out. So you're guaranteed 2 matches at least.
I think I'm D... In Privincial (state name in Canada), I usually lose my first match and my consolidation match. In Canada, it worked like that too when you lose the first match, you go into the loser of the first match batch. And if you lose you go out. You can also play all 3 disciplines.