I'm really digging this set... I see a number of interesting cards.
Shaymin EX - While completely useless in the early game unless you wish to risk an EX pokemon to energy accelerate, this can become completely killer in the late game. If your opponent have taken just TWO prize cards, the damage output is already 90, which is nice for two energy as it is. 4 prize cards? 150 damage plz, enough to KO a good majority of pokemon. 5 prize cards, or 180 damage, speaks for itself. Remember folks, only TWO ENERGY! IMO, this is meant to be a game finisher in a close match. Decks which lose pokemon fairly frequently like Mew Prime toolbox decks might ponder the idea in splashing in a Shaymin EX, which would work fine if Jumpluff is already being used as LZ fodder.
Leavanny - The new Exploud SF. Negating those pesky weaknesses of yours speaks for itself. Whether it justifies running a Stage 2 in a format where trainer lock will become a threat to all, though, is a different matter in itself. We'll have to wait and see.
Luxray - Can you say Flash Impact abuse with Reshiram/Zekrom/Kyruem's Outrage? Just might be possible... Maybe.
Mewtwo EX - I have mixed feeling about this card. On one hand, it looks like a great card. X-Ball has decent potential, but it also serves as its own desmise, as another Mewtwo EX kills with a PlusPower due to weakness, not to mention I firmly believe that Mew Prime toolbox will play a big part in the format. If it does, that only causes further problems for Mewtwo EX. In any case, I REALLY doubt that Mewtwo EX-centered decks will become any good just due to the sole fact that psychic-types are already becoming popular via Gothitell (sp?) and Mew Prime, both which will one-shot it for an easy 2 prizes. In the end, only time will tell.
Musharna - The new Uxie Lv X. Draw power is welcome, but it's a shame that Catcher iis in the format, now. Musharna may see most of its little use in trainer-lock decks.
Cinccino - Definately a FUN card to play, but I wouldn't put money on it being competitive. Coin flips are annoying.
Level Ball - Need I really say anything about how good searching for a pokemon with 90 HP or less is?
Skyarrow Bridge - Sure to be used in tanking deck like Steelix Prime.
Prism Energy - Usable in any basic-pokemon oriented deck that utilizing multiple energy types, namely Mew Prime toolbox.
Amoonguss - Obviously, this screams to be combo'd with Leafeon, but sadly, this will still not help with its problems. Rather than needing those Rainbow Energy for Roserade, now you'll need Seekers and SSU's to reuse Amoonguss's ability. Being an Eeveelution fan, I still intend to try this out, but I'm not hopeful about it. At least we don't have to worry about Power Sprays.
Gardevoir - A psychic-type version of Sceptile GE. What this finds itself comboing with will be very interesting to watch.
Groudon EX - I find this interesting. Not meta-changing, but interesting. Trample is a bit underwelming, but with it's second attack, it's also balanced. I'm neutral on this card, as it could go either way. Perhaps a good partner with Lucario?
Lucario - See above. It's ability sets up Groudon EX's second attack.
Weavile - Good tool-counter. Perhaps when Evolite becomes popular?
Shiny pokemon - It's good to see the return of shinies, and their art does not dissappoint.
Overall, I'm excited for the moment when these cards arrive in the US. There's lots of stuff to be tested.