Now that the full set has been spoilered, here's my take on what I'm watching for:
Baculin is like beedrill G all over again. It'll kill anything with 40 hp on the first turn, and with plus powers, can easily become a semi-viable donking opener, perhaps making decks like yanmega/zone unplayable
Luxray is nice being able to do 60 for 1 colored energy, but for a stage two, it'll take some resources to get running.
Mewtwo got enough hype already, not adding to that any.
Musharna looks great, until you read the attack (40 for PP AND self-sleep?!?) and the retreat (3 for a floating thing?)
Reuniclus actually looks kinda like a fun league deck, doing 40 x the number of Reuniclus in play for a single P
Conkwldurr is great with so much HP and a way to increase it, but we have too much viable psychic in this set to be worth it
Shiftry is interesting, but way too flippy for my tastes. If only victini allowed ability coin re-flipping too....
Ferrothron is a print of our EP card, which amuses me greatly.
Cinccino will be annoying, yes. I think this'll be our new gengar sf, in that we go after it with status conditions, or damage counter placement.
Level ball will be a staple, allowing you to search out basics and most stage ones, and certain stage two pokemon even.
Skyarrow Bridge is dodrio base in stadium form, it'll see plenty of play, lots of viable starter pokemon will love it.
Prism energy is interesting, but I can't think of any basics that NEED rainbow so much as just like it, exxcept mew. Maybe it'll see play in enabling a jirachi UL tech in decks like reshiram and zekrom, as well?
Foongus might be what Leafeon needed, a reprint of sorts of magmortar from SV. Pair that with Houndoom Prime(s) and you've got your 150 a turn for a grass energy.
Lapras will be a viable "starter" pokemon after rotation, 100 hp with a call for family attack is very solid.
Vanilluxe will see play, having the ability to "reverse warp point" is very strong, basically giving you disruption. Paired with dodrio, sky arrow bridge, or just a free retreater, it'll be like a circulator and switch every single turn, even under trainer lock.
Gardevoir has a surprisingly balanced attack, but that ability worried me with gengar prime still in format. Although, i'm not sure that it'd work, i'll wait for the exact English translation.
Groudon EX looks to be playable, water will be a bit more common next set, but still, the idea of hitting for 120 damage for FFC while having 180HP is very nice.
Lucario might have a home in some sort of four corners deck, to counter gigas EX, among others.
Weavile is too conditional, although it could fit into a dark toolbox as a revenge killer of people abusing rocky helmet and eviolite.
Bronzong makes Lunarock useless, and serves as a counter for anything abusing max potion and the new pokemon center
Wigglytuff paired with the Seismatoad line will be a viable deck, I'm sure of it
Gigas EX himself is rather playable, time will tell if he's tier one or tier two.
Heavy ball will give a speed boost to stage two decks like magnezone variants, emboar variants, gatr prime variants, etc.
Cilan will also give a boost to decks that have unlimited energy acceleration.
Pokemon Center will see a bit of play, but 20 a turn is kind of weaker than I expected.