Isaac would be a character with fairly typical or expected stats: his movement speed on the ground and in the air is very slightly faster than Shulk, while his attack speeds range from quick pressure tools to long damage dealers. Isaac would have a below average weight value, but drops like a rock when left to gravity. Undoubtedly, his greatest assets lie in his versatility.
STANDARD ATTACKS
Jab Combo
A: A quick slash.
AA: A quick slash, then another.
AAA...: A quick slash, then another, then a sudden burst of Growth Psynergy to attack the foe with vines.
Finisher: Isaac plunges a single large vine up from the ground.
Tilts
f. A: Isaac quickly brings his knee up into his opponent, a la Snake in Brawl. Locks at a lower percent.
d. A: Isaac hits foes with a brisk kick. Knocks foes into the air for combo potential.
u. A: Isaac draws his sword and performs a decisive upper thrust. Considerably long endlag time.
Dash
A: A large Psynergy hand bursts forth from Isaac as he stops in a shoulder tackle. Low range and knockback, but fast.
Smashes
f. A: Leaping slash forwards. Reference to his attack animation from Golden Sun.
d. A: Two stone and vine spires jut up on either side of Isaac as he crouches low. Loosely based on Thorn Psynergy.
u. A: Isaac performs a Psynergy imbued uppercut, creating a reverse-waterfall of rock. Loosely based on Rockfall Psynergy.
Aerials
n. A: A slow midair cartwheel surrounded by purple demonic spirits. Based on Haunt Psynergy, low endlag.
f. A: Isaac performs two spinning kicks in succession. Somewhat long start-up time and some endlag.
d. A: Isaac draws his sword into a powerful downward swing, a la Robin. Some start-up time, meteor smashes.
u. A: Isaac draws his sword and stabs up above his head. High endlag and long start-up, best used to KO opponents.
b. A: A quick backwards kick. Isaac's fastest aerial.
SPECIAL ATTACKS
Neutral Special
B 1.: Ragnarok. Isaac holds his hands up above his head and gathers Venus Psynergy, plunging a giant blade of energy into the stage. The player must hold down the B button to maintain the charge, then press it again once the charge has been completed to release it. Isaac can store the charge at any point by shielding, rolling, or waiting the full charging time -- similar in length to the charge time of Robin's Thoron or Samus' Charge Shot. Triggering the attack in the air will send the giant Psynergy sword in a somewhat more vertical path. A useful tool in Isaac's moveset that is great for keeping opponents away from stage ledges. High KO potential.
B 2.: Odyssey. Variation of "Ragnarok" attack. A shorter charge time that sacrifices the regular range of the attack. After charging, Isaac stabs forward with a giant blade of Venus Psynergy. The stab deals multiple hits and does heavy damage to shields, but lacks the angular projectile properties of Isaac's regular Neutral Special. Weaker KO potential, but the added option of shield pressure gives Isaac more tools.
B 3.: Titan Blade. Variation of "Ragnarok" attack. Much longer charging time, and an equally more impressive result to go with it. Isaac drops a giant Psynergy sword down on opponents a few character lengths in front of him, resulting in a devastating explosion. The move is a guaranteed OHKO should it connect, but its extremely long charge time and deceptively small initial hitboxes make such a thing a rare occurrence in the midst of a fight.
Forward Special
B 1.: Move. Isaac gathers Psynergy and projects a large hand forwards in a fluid motion. No damage dealt, put pushes foes away with a strong windbox effect. Covers just shy of half of Final Destination in length, making it a perfect tool for keepaway and harassment of offstage foes. Reflects lesser projectiles such as Fox and Falco's blaster shots or uncharged arrows from Link or Pit.
B 2.: Force. Variation of "Move" attack. Isaac quickly swings his hand forwards and projects a Psynergy fist to damage enemies from afar. Covers less distance, but its relatively low endlag and start-up time allow for Isaac to sneak in hits on those who aren't suspecting it. No longer reflects.
B 3.: Scoop. Variation of "Move" attack. Isaac gathers Psynergy and projects a cupped Psynergy hand along and through the ground of the stage. Covers the entire length of whatever platform Isaac is standing on when used; cannot be used in the air. Deals damage depending on how long the attack travels and how long opponents have been snagged by its hitboxes. Low KO potential, but can instead lead to massive amounts of damage if the attack catches and drags foes from one side to the other.
Down Special
B 1.: Gaia. Isaac gathers Psynergy and creates a beam of light that moves along the ground, bursting open into an explosion of rock and Venus energy. The player must hold down the B button to create the beam of light, releasing the button to trigger the attack. The player would have a limited amount of time to move the beam of light using the control stick before the attack would automatically trigger. Gaia naturally deals more damage to enemies that were hit by the attack when standing on the ground, dealing less damage towards the middle and little damage with no knockback to enemies at the upper edges of the attack. Cannot be used in the air. High endlag.
B 2.: Punji Strike. Variation of "Gaia" attack. Isaac gathers Psynergy and creates a beam of light that moves along the ground, bursting open into shoots of trapping bamboo. Opponents hit by the attack WITHOUT their shields up will take many low-damage hits that ensnare them in place, while those WITH shields up will face heavy shield damage that may lead to a complete shield break. Cannot be used in the air. Much less endlag to allow for combos. Controls are identical to Gaia.
B 3.: Annihilation. Variation of "Gaia" attack. Isaac gathers Psynergy and creates a beam of light that moves along the ground, bursting open into a bright flash of Venus energy and a fading kanji character (either 殺 (korosu) or 滅 (horobiru)). The attack has a 1/5 chance to deal heavy damage and knockback, but a 4/5 chance to deal no damage or knockback at all. Cannot be used in the air. Moderate endlag. Controls are identical to Gaia.
Up Special
B 1.: Planet Diver. Isaac draws his sword into a violent upper slash and soars into the air, crashing down to earth like a meteor. The attack follows a parabolic path when used, favouring vertical height on the ground or horizontal distance in the air. Correct use of the attack -- both on the stage and off -- is vital to Isaac's survival.
B 2.: Helm Splitter. Variation of "Planet Diver" attack. Isaac draws his sword into a violent upper slash, rising into the air before rocketing back down. The attack follows a vertical path, meaning it can be only used to recover safely when used below ledges. On the ground, Isaac performs a small jump and plummets back down, dealing heavy damage with longer endlag.
B 3.: Retreat. Variation of "Planet Diver" attack. Isaac draws his sword into a violent upper slash, disappearing in a burst of glowing Psynergy bubbles. Isaac then re-appears a moment later, moving in the direction the control stick was pushed, a la Zelda or Sheik. The slash is the only part of the attack that deals damage.
Final Smash
B: Judgment. Four Venus Djinn leap out from within Isaac as he raises his arms up, covering a few character lengths. If this initial attack hits an opponent, the Final Smash will trigger. The scene briefly changes to the sky, showing an angelic knight gathering energy into his shield before blasting it down. The scene changes again to the non-specific canyon seen in some of Smash's trailers, showing Isaac slowly lowering his hands into a neutral stance as whatever opponents hit by the Final Smash are engulfed in a giant explosion of blue energy behind him. The scene then cuts back to regular gameplay as the opponents are knocked away and the fight continues.
GRABS AND THROWS
Z: Isaac uses a Psynergy hand to grab a foe. Very easily punished if Isaac misses. Based on Catch Psynergy.
A: The Psynergy hand tightens its grip to deal damage.
f.: Isaac blasts them away with the Psynergy hand. Based on Move Psynergy.
d.: Isaac raises them up and slams them down with the Psynergy hand. Based on Pound Psynergy.
u.: Isaac tosses them up into the sky with a second Psynergy hand. Based on Lift Psynergy.
b.: Isaac quickly crosses-up and blasts them away with the Psynergy hand. Based on Move Psynergy.