These videos also help show the psynergy attacks that Isaac is able to do in action.
Keep in mind that from a gameplay perspective, Felix (the brunet guy in the video and the main character of the second game in the franchise) fills the role Isaac had in the first game so pretty much anything he can do, Isaac can do as well.
How does his moveset potential translate to the potential for a unique gameplay? First;y, his "hand" magic, due to the various forms it takes, can be translated into a projectile with multiple follow-ups including the potential to turn into a grab attack.
His various earth-based and plant attacks tend to mostly emerge from the ground, thus meaning his projectiles would mostly have a non-standard trajectory in comparison to other projectiles-instead of being mid-profile projectiles that simply goes forward, they are low-profile attacks that would work great as a form of anti-ground attacks, launching them upwards.
His Djinns are were he really shines as they help give him another unique mechanic-a powerful summoning cycle. There are three states of the Djinn- The "Set" state, the "Standby" state and the "Recover" state. The set state is where a Djinn is active. Regardless of the various types used, when unleashed, they can either boost Isaac's stats temporarily, deal a form of damaging attack or heal Isaac.
If unleashed, each Djinn is then put on standby. The number of Djinn being set on standby and the types determines the types of summons available, based on how powerful they are (and the element they are). For the sake of simplicity, let's stick to just Venus(the one associated with earth and plant magic) Djinn. One Venus Djinn on standby means the
Venus Summon can be activated, two means
Ramses, three means
Cybele and four means Judgement.
After being summoned, the Djinn are then put into recovery mode for a time proportionate to the power of the summon. This could be translated into Smash as Isaac's stats becoming lower all-round (power, speed, etc.) with how weak he is overall being based on the power of the summon he unleashed
I believe that Isaac has the potential to be a projectile-based rushdown character due to the type of magic he is using feeling more in-your-face with the potential for temporary stat boost and levelling-based summoning system with a high-risk-high reward aspect (more rushdown-power for minimum defense).
I hope I informed everyone of what Isaac could be capable of within the context of Smash.