A brief overview of the current meta:
Origin Forme Palkia Vstar, probably the #1 deck right now, attack can hit for up to 260 damage and a pretty op Vstar power where you get to attach 3 water energies from your discard pile to your pokemon. Usually partnered with the Inteleon engine from sw/sh base set.
Arceus Vstar is probably the most versatile mon in the meta right now, attack hits for 200, searches for 3 basic energy to attach to your pokemon Vs. Oh, and did I forget to mention the Vstar power that lets you search for ANY TWO CARDS in your deck! Can be partnered with so many cards, such as the aforementioned Inteleon line or Flying Pikachu Vmax as a counter to Palkia.
Mex Vmax is insanely aggressive and fast to set up, using Genesect Vs ability to draw tons of cards, and it can copy usually Genesect Vs Techno Break for 210 damage or Meloetta's attack (blanking on the name) for up to 280 damage!
Anyway, you can find lots more info about the current meta, budget decks, upcoming sets and other stuff at
www.justinbasil.com. Hope this helps!