I have no idea what exactly his moveset coud be, but I'm 100% sure that he has growth in it. (Just look at this teaser)

And he'd be not Isaac if there were no Ragnarok and Spire. Maybe Odyssey.

But here's my speculation:

Neutral B: Maybe some field Psynergy like "Move" (Everyone knows that from Brawl), or that you can change the Move by pressing up/side/down while charging into force/pound/scoop/carry.
Side B: Odyssey or Ragnarok; (Giant Sword) Odyssey would work similar to Lloyd's side b, dunno about Ragnarok
Up B: Spire. (Create a stlactite under himself and jump off, thowing the rock down) Yes, I'd say it's his up B and would be like sonic's but with a much weaker recovery, granting him just one more jump (or maybe even doublejump)
Down B: Quake Series; Maybe chargeable, he hits the earth around him to shoot out and retract quickly, the more charged, the more (often) earth comes out.

Grab: Growth. He grabs enemies with vines from a distance.
Throws: Different Djinni (or lvl 1 Summons). Nuff said.

Normal Attacks: Swordplay, and maybe a bit enhanced swordplay.
Tilts: Different Unleashes/Djinni (of the throws would be summons)

Ultra Smash: Grand Gaia. It'd be similar to a reversed PK Starstorm, rocks coming from the earth with high speed. Why not Judgement? It'd be too much of an overkill, imo.

Taunt: Set Djinni/Take out Mars Star

Is Isaac going to be canon?

that is the question.
...
...

Isaac full of water and wind and Mind read and Hover and Ply and Tempest and Teleport and Halt and Cloak and Force and Shuriken and Deluge and Frost and Douse and Avoid and Boreas as a Final smash.

- SSF2 2014

Geno Make it happen son. please Geno-Chan

If Isaac was to play like in the games, he would probably use an sword, dijinni, psynergy, and summons.
I think it would be somewhat like this:

http://www.youtube.com/watch?v=RXehwMIJ2Vk

I hope he'll be assist based, Summoning Djinns and his party members. his main attacks will revolve around him utilizing psynergy to swing his sword. Or maybe He'll be similar to how Sora used to play, Changing Djinns with down-special, and using neutral-special for different attacks based on the djinn selected. I think his Up-special will be sort of like MegaMans, by him hanging onto the Jupiter Djinn and flying upwards a short distance.I really want the Final Smash to be the judgement summon though! Similar to the final hit of Blackmages old final smash. Something like judgement appearing in the background and unleashing his Lion Cannon! However they make him I'm sure he'll be a solid character with a great movepool!

Isaac will more likely be similar to Ike from Brawl.
He is also most likely to focus on Venus psynergy, with a spatter of mars.
If Isaac stays true to the GoldenSun series about the Djinn cycling, then we can expect a similar system to Naruto's Dspec.
Specials will focus on Djinn and psynergy, while Attack will focus on swordplay.
Grabs and tilts will be a combination of the two.

Well, thats just my guess. Any other presumptions?

Is no one hype for Isaac anymore?

Its been 3 and a half months since someone has speculated at all, hell he's literally never brought up in the IRC.
0.9c should happen before Isaac fades from existance

Personally I dont have any idea how his move set would work (ive never played Golden Sun)

No ones hyped because 0.9c is taking longer than the second coming of christ. You can only speculate so much before it just gets boring. It's like thinking about your christmas presents in april.

I just really hope they don't make him entirely magic based.

I want some sword swingin and magic dealing; just give me a Marth/Ness mixup, and I'll be hooked.

So basically Robin?

(although I'd like to see how a disjoint DJC character would work... but i doubt thats happening in this case)

This.
It's best that we just wait to see happens at APEX.

Why not make some predictions about what we are gonna see from that character at apex

Neutral Special: Grand Golem(Charge up rock punch)
Side Special: Rock Slide ( A diagonal slide of rocks from above isaac)
Down Special: Earthquake ( Similar to Donkey Kong's but you hold down the special button)
Up Special: Sabre Dance ( Similar to fox's but with multiple sword slashes )

Standard Attacks: "Attack" with Gaia Blade

Side Smash: Use a more powerful "Attack"
Down Smash: Mother Gaia surrounds Isaac
Up Smash: Stone Spire comes up from the ground

Grab: Catch
Hit Whilst Grabbing: Grind
Forward Throw: "Carry" Forward and then throw
Back Throw:"Carry" backward and use Odyssey
Down Throw: "Carry" downwards (pin the opponent against the ground) and use Tremor
Up Throw: Let go of enemy then use Scoop and throw earth at them

Kinda not worth predicting the moveset, it's impossible to predict exactly what moves they will give to Isaac when the new version is shown.

This is a speculation topic - predicting things you can't know for sure is kind of the point.