Here are the decks that will most likely be played at worlds:
Seismitoad-EX: This deck can be combined with Crobat, Manectric-EX, Garbodor, or Giratina-EX.
Primal Groudon: Use Robo Sub to stall while charging up the massive Primal Groudon-EX. Then do a massive Gaia Volcano.
Primal Kyogre: Primal Kyogre-EX has a nice balance of attack and defense. 240 HP makes it difficult to Knock Out, and Tidal Storm deals big damage.
Mega Manectric: Use Turbo Bolt to attach a bunch of energies, then swarm the opponent with an army of charged Pokémon. Garbodor can use Garbotoxin to shut down all of those pesky Abilities that get in the way.
LandoBats: Use Strong Energy, Fighting Stadium, and Muscle Band, to increase Landorus-EX‘s attack power. Crobat does Surprise Bite to do some extra damage to opponent’s Pokémon, and Hawlucha takes care of the EXs.
Night March: Battle Compressor out your Pumpkaboos and Lampents so Night March does lots of damage, then hit hard with Joltik. This deck is simple but very strong.
Virizion/Genesect: The combine Virizion-EX and Genesect-EX to do massive damage. Use Emerald Slash to power up big Megalo Cannon and G Booster attacks!
Klinklang: Accelerate your energy with Bronzong while stalling against EXs with Klinklang. If you need to do damage, use Ageislash-EX, Heatran, and Cobalion-EX.
Archie’s Blastoise: Use Archie’s Ace in the Hole to set up Blastoise, then accelerate energy onto Keldeo-EX with him for big hits.
Raichu Bats: This deck uses a bunch of things to do damage. Raichu, Crobat, Hawlucha, and Landorus-EX.
Wailord: Use about 7-9 Pokémon, 0-2 energy, and about 50-53 Trainers. Use Wailord and Suicune to stall, and use Landorus-EX as a last resort.