I personnaly am in favor of a gimmick mechanic with the djinns.
If it's allowed to go
bonkers on it, here is my version of Isaac:
General Gameplay:
-Mid range area control to rack up % but needs to get close to deliver a killing bow.
-Somewhat high micro-management of the gimmick ressource: djinns.
- Stronger on the ground, but has a pretty solid recovery (will come to it)
-Possible change of some specials/other attacks depending on what djinns are equipped. Having 2 djinns set increases the range and charging speed for the specials. If no djinn is set, he'll default to the weakest version of his venus attacks. If too complicated, just resort to Venus attack (except when specified otherwise)
Special UI displaying Djinn status:
Specials:
Neutral Special: Uses the selected Djinn (2 per element, 8 total with different effects listed below)
Venus: Flint: A heavy knockback attack, one of Isaac's strongest killmove. Medium recovery time, no use outside of the attack. It comes out faster when isaac is on the ground.
Ground: Buries opponent close to Isaac to create an opening. The range is rather short and there is a delay before the gravity orbs comes down, it can be shielded or dodged. If used in the air, it will spike.
Mars: Forge: increases Isaac's physical damage (but not knockback) by 25% for 10 seconds, in team versus, affects his nearby allies as well.
Flash: Reduces the damage and knockdown of the next attack taken by 90%, the shield lasts 5 seconds but comes out instantly. Long recovery.
Jupiter: Kite: The next used special will be doubled. Replaying instantly without recovery frames. Some can be triggered midway through. Long recovery.
Luff: Seal's all the opponent's specials for 5 seconds, expect recoveries. Long recovery, midrange projectile, the djinn rushes forward, if it touches, it will take a short animation to seal the specials, during which the opponent can still use them. Long recovery
Mercury: Sleet: Short range projectile that reduces the damages inflicted by the affected targets by 25% for 10 seconds. The projectile is a fluid affected by gravity, similar in visual to Inkling's ink.
Eddy: Fasten the recovery of all other djinns currently in recovery, longest cooldown by far.
Side Special: The function stays relatively the same, but could change depending on what djinn is currently set on Isaac.
Venus: Quake, a short stone "wave" on the ground. Does not work midair, unless there is ground directly below Isaac. It'll be disjointed and the height will be unchanged. Medium damage, but strong vertical knockback.
Mars: Flare, a spray of fire forward. High damage but weak knockback.
Jupiter: Ray a longest lasting hitbox of electricity. Almost no knockback, but it does keep the targets in place thanks to the multihit. Giving a change to dash attack or grab.
Mercury: Frost, an icy wave on the ground. It shatters once it reaches its max range, doing a second, weaker, hit. All of the same range. Just different properties. Chargeable, increases the range.
UP Special: Vary strongly depending on the current djinns. If simplified, go with the Jupiter version.
Venus: Rockfall. Isaac steps on a large boulder materialising under his feet and use it a step ladder for a small jump. Upgraded version has him jump twice. Boulder falls and damages those under it. This is is weakest recovery, but is the best for ledge guard, as it can spike opponents recovering low.
Mars: Planet Diver/Planetary: Similar to Incineroar UpB, planterary causes a large explosion on impact, and goes higher and further. High risk high reward recovery, more intended to be used for aerial mixups to get to the ground quickly.
Jupiter: Hover. Isaac's conjures a platform restoring all of his aerial mobility (double jump, air dodge), with 2 djinns it can be reused indefinitely. He is vulnerable while on it. Strongest recovery, especially with 2 djinns. But easily punishable. Unlike Steve's block, Isaac cannot do a smash attack while on it.
Mercury: Froth: Isaac forms a bubble around him, giving up a multijump similar to kirby's. The jump are higher with 2 djinns. The bubble can be destroyed by attacks. While pretty slow, the bubble protects Isaac from one hit (if it doesn't exceed a certain %, for example 15%) he would be stuck in freefall after it is destroyed.
Down Special:
Djinn selection. It opens a menu in which you'll choose which djinn to set for your Neutral Special. You cannot move while selecting, and each element will affect Isaac's stats (weight, fall speed, ground and air speed...) swapping in the air can change how fast he'll continue to fall.
When a djinn finishes cooldown, a colored light will flash on Isaac along with a sound effect and his HUD updating.
Final Smash
Summoning: Isaac will perform a cinematic FS doing a summon that depends on his current djinn setup. It is purely a visual change and a damage type change (so some summons may not damage pikmins).
The possible summons being Judgment, Meteor, Thor and Boreas.
It starts by the djinns swirling around Isaac, upward, scooping opponents even behind. It puts half of his djinns in recovery.
Normal Moves:
Neutral/Jab: Three hit combo. Downward slash, upward slash ending with the sword above his shoulder, then using "Move" to push the opponent away a
SET distance (not affected by damage, djinns etc).
Dash Attack: leaping sword strike, emulating his GBA attack animation. The leap has a pretty long reach and hits fairly hard.
Side Tilt: Slap, a psynergy hand slap that deals low damage but can reflect projectiles and turn still opponents arounds, has a pretty long recovery to avoid spamming.
Up Tilt: Simple arcing sword slash.
Down Tilt: Psynergy changing depending on djinn setup:
Venus:Spire: A stone spike rises in front of Isaac and strikes diagonnaly away from him. It has physical existence on the field and will stop projectiles during the animation. It can be destroyed by strong attacks/projectiles
Mars: Blast, short range explosion that launches far at a very low angle.
Jupiter: Whirlwind, small tornado that launches straight up but does very little damage.
Mercury: Cool, same as spire but reflects energy based projectiles, shatters on physical ones.
Side Smash:
Venus: Ragnarok. Similar to Bayonetta's Side smash, but conjuring an energy sword from a transmutation circle instead. Isaac's farthest reaching "physical" attack. With 2 djinns, becomes Odyssey, a 3 hit attack, first are two smaller blade impaling the opponent in place before striking with a giant one, lower reach for more damage.
Mars: Juggle/Fiery Juggle. conjures a circle of fireballs, with 2 djinns it conjures more, faster. They appear behind Isaac and are launched forward on release, slightly toward the ground.
Jupiter: Astral Blast/ Thunder mine: A colorful starshaped projectile strikes in front of Isaac. With 2 djinns it launches a giant thunderball which explodes on impact.
Mercury: Cutting Edge/Plume Edge: A short lived shockwave, which becomes a two timed attack with two djinns, the first trapping the opponent in water if it connects, before isaac strikes.
Up Smash:
Venus: Gaia, several small rocks lift from under isaac and are launched up right above him.
Mars: Fire, a swirl of fireballs are launched upward.
Jupiter: Wind Slash. A succession of wind blades over a short distance above Isaac, upward.
Mercury: Ice Horns, same as Gaia but with Ice Shards. Same range, different properties.
(Gaia keeps the opponent rather close to the ground, Fire can set them ablaze, Wind Slash pushes them further up and Mercury is somewhere between gaia and Wind Slash)
Down Smash:
Venus: Briar/Nettle, Thorny briar rises from the side toward Isaac, joining just above his head. Their thorns are bigger with 2 djinns, increasings the damage. It scoops opponents toward the center, similar to Roy's up smash.
Mars: Volcano/Pyroclasm Column of fire centered on isaac, two additionnal pillars if 2 djinns. Sets ablaze and has a low vertical/medium horizontal knockback.
Jupiter: Plasma/Shine Plasma: Lightning bolts striking next to isaac. Get bigger with 2 djinns. Knock straights down, making opponents bounce on the ground (could be techable)
Mercury: Prism/Hail prism: Giant ice blocks tossed on the ground, with two djinns a second one falls behind Isaac.
Aerials:
Neutral: A spinning slash, hitting first right behing him, before ending behind again with more range and power.
Forward: An horizontal slash from his left to his right, similar to Roy's but in one single strike.
Back: A jab behind him, purely horizontal hitbox.
A sweeping strike right below him with great horizontal reach, does spike at the exact center.
Grabs:
Grab: The "Catch" psynergy, fairly long range especially for a swordfighter.
Pummel: The hand squeezes the opponents.
Forward Throw: The "Force" Psynergy is used to punch the opponent away with a big telekynetic fist.
Back Throw: The "Grip" Psynergy pulls the opponent behind Isaac and launches them after passing by him.
Up Throw: The "Scoop" Psynergy launches them straight up!
Down Throw: The "Pound" Psynergy hammers them into the ground.
Classic Mode:
The Angarian Journey:
Reconstitute important fights from the first game. All are Endurance fights.
1st: Vault's Thieves. A fight against 3 thieves type characters (3 Sheiks for example) on a town map like Animal Crossing ones. Smokebombs appear regularly.
2nd: Kolima's Sacred Tree. A giant Ivysaur on Dreamland.
3nd: Saturos. A Duel against a blue color Roy atop of a tower stage (Mercury Lighthouse if Isaac's stage is the Lighthouses are his stage and can be swapped between all of them), possible stage could be the Plateau's Sheikah Tower. Fire Items spawn regularly, mostly Fire Flowers and X-Bombs. Roy's Fire attacks are increased.
4th: Mogall's great ape: A giant Green Donkey Kong and 2 Diddy Kongs. Screen could be reversed occasionaly to reflect the maze like-forest.
5th: The Colosso Finals: 3 Fighters in a row in the Arena. Likely Marth, Chrom then Ike. Some items (smoke bombs, food, Bobombs) can appear on the stage, that the opponents will rush.
6th: Saturos and Menardi: Blue Roy and Red Zelda. Zelda starts with a Death Scythe. This time the fight takes place on Venus Lighthouse.
7th: Rathalos Boss. Refers to Saturos and Menardi transformation into the Fusion Dragon.
6 and 7 could be replaced this way: 6th: The Ghost Pirate, Ganondorf on a Ship based stage with super armor.
7: Saturos and Menardi, but once Defeated spawns Ridley and Charizard to Emulate the Fusion Dragon.
Misc.
Palette would just be party members color. Colors 5 to 8 would be party members from the 2nd game.
Holds item with a small psynergy hand.
Taunts: Victory pose from the 3rd game, sword pointing to the ground, hands on the pommel.
Djinn acquisition animation.
One of the game's emote speech bubble pops above Isaac's head.
Victory animations: Isaac lifts an obstacle that was covery the camera with "Lift"
Isaac's runs after a djinn, trying to catch it.
Flint float's around Isaac before nestling in his scarf.
And here we are.
If I totally misunderstood how to do all of this, well...curses ! xD