I just started playing a bit, but I do know a few new things.
1. lv. X cards can be used to upgrade your Pokemon. While a Pokemon is in lv. X form, it can use any attack/PokePower/PokeBody from it's previous form. Plus, they come with more HP and attacks of their own. lv. X cards count toward the limit of four of each card. For example, you cannot have four Infernape and one Infernape lv. X. When you are asked to remove the highest stage Evolution card from your Pokemon, you must remove both the lv. X card and the previous form. lv. X Pokemon are sometimes reffered to as "Level-up Cards".
2. There are now attacks that can be used for no Energy cost. They are represented as a gray circle. They usually are found on Basic/Baby Pokemon and do little to no damage.
3. Stadiums and Supporters are now seperate cards from Trainers. When you are asked to search your deck for a trainer card, you cannot search for a Supporter card or Stadium card.
4. Dark and Metal Energy are now Basic Energy cards.
5. I don't know that much about strategy since no one plays with me, but here's mine: If at the started you have a powerful Basic Pokemon in your hand, Bench it. Save it for later, and keep slowly building up Energy cards on it. When the time is right, UNLEASH YOUR POWER!
I hope I've been a help.