Sure, I'll take a crack. Greninja has a history of low-cost, interesting-effect attacks, but I *think* both its regular attack and the GX attack are [W][C][C] from what I can make out? I also think I can make out a 1 retreat cost. The GX attack doesn't seem to have a base damage, but I think I can make out *some* sort of number for the main attack? No idea what it is, but I get the sense it'll be north of 100 base. And I wouldn't be surprised if it continues the new Frogadier's theme to give us our effective "bats" replacement.
Therefore, a guess:
Greninja-GX - Water - HP230
Stage 2 Pokemon-GX - Evolves from Frogadier
Ability: Ninja Strike
When you play this card down to evolve 1 of your Pokemon, you may place 4 damage counters on your opponent's Pokemon in any way you like.
[W][C][C] Silencing Blow - 130 damage - The Defending Pokemon can't attack during your opponent's next turn.
[W][C][C] Shuriken Storm GX - Discard as many [W] Energy from your hand as you like. For each [W] Energy discarded in this way, choose 1 of your opponent's Pokemon and deal 50 damage to it. (Don't apply Weakness and Resistance to Benched Pokemon.) (You can't use more than one GX attack per game.)
When 1 of your Pokemon-GX is Knocked Out, your opponent takes 2 Prize cards.
weakness: Grass x2
resistance: none
retreat cost: [C]
I'm sure we'll get the reveal soon enough.