Jab combo: Douse, followed up by Frost - attacks quickly with two jets/whips/waves/whatever you wanna visualize of water, then freezes both and stabs them forward.
Forward Tilt: Fire - Creates a short, small explosion directly in front of Isaac
Down Tilt: Growth - Causes several thorny vines to grow out of the ground and lash out
Up Tilt: Gale - A current of wind that launches foes upward
Forward Smash: Avalanche - Boulders float around Isaac as he charges. Unleashing the attack causes the boulders to slam together in front of him
Down Smash: Glacier - Bubbles of water grow on either side of Isaac as he charges. Unleashing causes the bubbles to freeze and explode into shards
Up Smash: Lava Plume - The earth starts to smoke under Isaac while charging. Unleashing causes the lava to shoot out of the ground
Neutral Air: Whirlwind - Causes blades of wind to slash around Isaac
Forward Air: Sonic Slash - Creates a giant blade of wind in front of Isaac
Back Air: Supercool - Fire a small burst of ice shards behind Isaac
Down Air: Blast - Fires a concentrated blast of fire downward
Up Air: Bolt - Fires a small burst of electricity upwards
Grab: Move - Shoots out the giant hand everyone knows from Smash Bros to grab enemies. Pummel would simply squeeze the opponent ala Master Hand.
Up Throw: Froth - Traps the opponent in a bubble and sends them slowly drifting into the air. Slowly take damage as you "suffocate", until you break free
Forward Throw: Plasma - Fires a bolt of Plasma, shooting the opponent forward
Down Throw: Quake - Opponent is planted into the ground, then the earth juts upwards, sending the opponent flying
Back Throw: Nettle - Vines grow out of the ground and whiplash the the opponent backwards
Neutral Special: Earthquake - Strikes the ground. Nearby grounded enemies trip. If used Airborne it becomes Storm Ray, which momentarily stuns nearby airborne enemies
Side Special: Stone Spire - Charges up, then causes several stalactites to shoot up in a line in front of him. Airborne shoots out icicles
Up Special: Deluge - I'm not feeling inspired for this one, just steal Squirtles
Down Special: Bind - Tosses a small sphere of energy forward after a delay. If it hits, it prevents opponents from using Special moves for a few seconds
Dodges: Cloak - Hides in the shadows as he dodges and sidesteps.
Shield: Gaia - Encases himself with Earth
Final Smash: Call Demon - Use your imagination :D
Not gonna bother with taunts. I think that's everything, sorry if I missed something, I'm tired
I could make several completely different and unique movesets off of the psynergy alone. NOBODY who knows Golden Sun will take you seriously if you say there isn't enough to differentiate him, the complete opposite is true.