New to the game. Sets allowed?

[Getalinks]

So, I've been playing for about 3 weeks now and I was reading the tourny manual on the main site. It said something about certain sets are allowed in the circuit this year?

I'm confused. Can I only use certain sets each year or something? Can anyone explain this to me, please?

[PokePop]

Here, this was updated fresh last night for the new Modified format which takes effect on Saturday, September 1st: http://pokegym.net/forums/showthread.php?t=41415

[Getalinks]

And that's going to be the list to use all year til GenCon Indy? (By the way...thank you! :D)

[PokePop]

That link, yes.
Note that as new sets come out, sometimes an old card is reprinted and gets added to the list.
For example, Diamond & Pearl reprinted Plus Power, a card originally from all the way back in Base Set! Granted, it has had some text changes (the original one was translated badly) and so needs a reference in order to play it, but I've heard rumors about some other good old cards being reprinted in upcoming sets. They will all be updated in that list as they become legal.

[TrueCharizard]

I bought the Feraligatr Epic Collection deck, is it still legal?

[PokePop]

Some of the Trainers are. It goes by the set symbol printed on the card.
But some of those Trainers have been reprinted in later sets.