Got to love the new possibilities for the game with this set. First, you have the Ancient Traits, the most powerful of which at this time are Omega Barrier and Alpha Growth. The pluses for both are pretty clear, as follows:
Omega Barrier
- Great for countering Lysandre, Startling Megaphone, Enhanced Hammer & the like
- Makes for a devastating shield if used in conjunction with an ability-erasing effect
- Can be used to set up the field for a big play
Alpha Growth
- Allows you to potentially set up automatic KO's
- Makes for devastating hits out of nowhere
- Can be used to come back from a bad start, and pull further ahead when you're already ahead
There are ways to use both of these right now, though Omega Barrier is by far the more splashable of the two due to Rhyperior's ability; that said, Alpha Growth is going to be Water exclusive unless you count strategies in Aromatisse, Hydreigon and Electross decks. Moreover, Omega Barrier will likely be extraordinarily useful to the fighting type, as you can literally pull off a walling strategy with Groudon EX/Korrina/Healing Cards, forcing your opponent to do a full knockout or be delayed for many turns while you just set up to win. This actually includes the Grass type, even though Groudon EX and Primal Groudon EX are weak to it; the only good attacks that can actually stop the titan are from Genesect EX and the new Trevenant EX, though both require at least two turns of setup to do so, assuming that you aren't playing Team Flare tools which completely destroys the need for Weakness Policy in the matchup. Furthermore, Omega Barrier allows you to use special energy cards far more loosely, and will definitely allow for plenty of leeway on how to build the deck of your choosing.
Let's not forget to point out Garbodor builds yet, as Omega Barrier, Alpha Growth, and to an extent Multi Strike have great synergy with ability lock. Omega Barrier will further lock your opponent from doing anything at all to your field, Alpha Growth is always going to help you attach energy at critical moments, and Multi Strike will be allowed to do maximum damage. We'll just have to wait and see what the future holds for Ancient Traits in the coming months.
As for other content in the set, we have the possible return of the Water type in a wide slew of cards, the most prominent being Swampert. Not only are you able to attach two energy a turn to it without effects, it can search your deck for any card and put it on top of your deck for free. using this tactic, you can set up for an Archie's Trump Card, allowing you access to many possibilities to overwhelm your opponent.