For my platform fighter, I decided to just make a big list of all the mechanic changes and additions from a standard platform fighter like Smash Bros:
No Ledges: No ledges will be in this game, I feel modern Smash Bros has gone down a more campy overly defensive playstyle, so the lack of ledges will theoretically make things more aggressive and therefore more entertaining.
Separating Dodges and Shields into Two Separate Buttons: Due to mechanical changes to how shields work, I decided to separate shields and dodging into separate buttons. Dodging allows you to either do a standard spot-dodge, a directional air dodge, or a ground based dodge roll. Dodges are also what allow you to wave dash in this game, meaning no mis-inputting shields because...
Shields are Now Tied into a Meter Mechanic: Every fighter has a 5-segment meter that fills when you either deal damage to opponents or receive damage yourself (though the meter growth is slower when you are just damaged) You can spend a section of meter to enhance one of your Special Attacks into Hyper Specials, which are either stronger or have unique applications the base Special can't perform. You also spend a section of meter to cast a shield, and you will be stunned if the segment gets depleted before you pull the shield back. Finally, the free shield button lets you shield in the air, which is stronger than a ground shield, but you will be pushed back more, and the shield will disappear when you touch the ground. Parrying can be used to partially recover some meter energy. When you have 1, 3, or 5 segments of meter, you can also perform 1 of 3 Hypermax Attacks, unique and powerful attacks coming in three levels based on how much meter you have.
Wavedashing and DACUSing return: These two classic advanced techniques return with minor changes. DACUS can now be used for all directions of Charge Attacks (the equivalent to Smash Attacks), so you could see it as now Dash Attack Cancel Charge Attack, or DACCA. Wavedashing is mostly unchanged.
Custom Stage Lists: You can save hazardless and hazard versions of each stage under a custom list, letting competitive players have more options in stage choices and not have situations where Battlefield/Smashville is too similar to Yoshi Story/Hollow Bastion to be worth using as a competitive stage choice.
Taunt Changes: First you now have 4 taunts, one for each direction, AND you can use them in online battles now.
These are the most notable changes from Smash Bros' main mechanics, how does this look so far, may add more.
I've personally held a belief for ages that Araki discovered Wikipedia midway through writing part 6 and never really looked back? Hence why a lot of the abilities going forward are a lot more esoteric in some ways.
That said, userless Stands are such a cool thing to work around and really shake up the formula in a cool way that automatic Stands aren't quite capable of. Les Feuilles is a good example of this in my mind.