azukola

azukola, There are only 4-5 errata'd cards in total iirc. You aren't likely to use any of them anyway except maybe for Rare Candy, but just so you know they are Potion, PokéBall, Rare Candy, Pokémon Catcher and something else I'm forgetting.
You're welcome

azukola, It was errata'd, so it's legal. Both Catcher and Lysandre have the same effect, except that Catcher requires you to flip.

azukola, Basically Lysandre is a Pokémon Catcher without a coin flip, whole Catcher requires you to flip heads to work.

azukola, You're welcome

azukola, Here: http://pokegym.net/forums/showthread.php?41415-Standard-and-Expanded-Format-Legal-Card-List-Discussion
There you will find a list of all sets currently in existance, along with which cards from each set are legal for play.

Yup, the only thing it doesn't apply to is to Pokémon. Ex: Raikou-EX DEX was rotated out last year. If TPCi was to print another Raikou-EX, but with, say, 200HP, the DEX version wouldn't be legal for play. However, if TPCi made another Raikou-EX with the exact same HP, attacks, Weakness, Resistance and Retreat Cost, the DEX one would be legal for play.
You could also take a look at this thread: http://www.pokebeach.com/forums/thread-what-cards-are-legal

azukola, You're welcome!

Hey, welcome to PokéBeach!
If you need any help with TCG stuff, feel free to ask! ^.^