Yay a response!
Hmm, okay so assuming I have full pull here, I'd want to differentiate it significantly from other fighting games. The problem is it's been years since I played one so I'm not sure what the state of the art is in the first place.
I'm thinking an emphasis on level design. Not just a flat static floor the characters fight on, no. Lots of 3D buildings, opportunities for Parkour with room for Force Jumps, grapple guns, and other fun stuff to help the characters move around. Possibly destructible terrain to add some tactical fun in taking down buildings or platforms to deny them to a more mobile opponent.
No Fighting Game is worthwhile without a versus mode, I'd also include a story mode. Might include some weaker mooks in order to let it expand into a beat 'em up in story mode, add some stormtroopers, reskin them as rebel troopers, and some Gammoreans.
That's actually a good idea for the story mode. It's a very arcade way of doing things as well, harkens back to the classic arcade games where you'd dispatch of large numbers of mooks across various levels, before fighting a boss battle.
Character Roster:
We'll start with 8 playable characters, with five hidden characters that are antagonist-only in Story Mode. They will become playable in the first DLC. The reason for limiting the roster so much is so that we can spend more time on refining and balancing each of them, hopefully resulting in better initial gameplay. Later DLCs can add more fan favorites.
The size of the roster is right in line with old school fighting games like the original early Mortal Kombats and Street Fighters etc. Even Super Smash Bros. only have a roster of a dozen characters. Nowadays, fighting games really do depend on fighters as content, which is understandable but there is a very real issue, as you note, with derivative characters. Especially in a first run and especially with a verse where the power sets for many characters is very familiar.
Sustaining interest through paid DLC would be a legitimate way of sustaining the game over years though as the gameplay is hopefully improved and growing pains eventually hopefully falling aside.
Darksiders:
Darth Maul
Darth Vader
TR-8R
Asajj Ventress
Boss Enemies:
Emperor Palpatine
Darth Talon
Sith Rey
Lightsiders:
Luke Skywalker
Ezra Bridger
Ahsoka Tano
Chewbacca
Boss Enemies:
Yoda
Bultar Swan
Lightside Rey
The Reys are just recolors to save on design, but allow us to use her on both tracks so no matter what you play, you get a chance to kill Rey, not that I'm putting it that way in the board meetings.
This roster is designed to give a decent mix of styles. On the darkside roster we have a dual-wielder, a lightstaff user, a single-blade user, and one non-Sith mundane. Honestly could probably do better but TR-8R is pretty memetic at this point. The lightsider roster similarly has a single-wielder, a dual-wielder, Ezra has a lightsaber that's also a gun so ranged, and Chewbacca for our mundane, equipped with Rykk blades and a Bowcaster. Bosses were similarly chosen to be different, Yoda's super small and fast, Palpatine is a sorcerer type, Rey has her weird jack knife saber, Darth Talon is very acrobatic without being as small as Yoda, and Bultar Swan is a barehanded Jedi.
Bultar Swan is possibly an iffy choice. She's notable for being a Jedi who eschewed a lightsaber in favor of beating all her problems to death with her bare fists but she hasn't really been in that much media so may not have the star power for this roster. I'd prefer another lightside female for cheesecake DEI purposes but nobody's really coming to mind. Ayla Secura would work but there's not much mechanically to make her anything but a reskin of Darth Talon.
We'll include a limited number of levels for the same reason, extra detail on making them shine rather than going for quantity. One level will need to be boring and flat for tournament purposes, the rest can be interesting.
I was legitimately surprised at who the picks were but as you lay it out, it definitely makes sense. I had to look up Bultar Swan as it's one of those characters who you think you might know by name but your not sure. But why you added her makes perfect sense. Also despite the small roster, you managed to get all of the important and iconic characters mentioned like Luke, Vader, the Emperor, Rey, Ahsoka, Maul etc so it should generate enough fan interest.
When you brought up Aayla Secura and Darth Talon, there is a concept in fighting games called 'Echo Fighters' which is actually used to a considerable amount of success. Games as different as Super Smash Brothers and Netherrealm's Injustice use it, which is where you have characters with pretty similar movesets and appearances, but you still change other things like stats and even hit boxes and the like, as well as completely redone reskins, voice lines, story modes etc so they are still fairly different characters. They might even have different summons or final combos or other ancillary powers. It's how Super Smash Bros can have regular Mario, Feline Mario and Dr. Mario... or how Captain Falcon and Ganondorf were initially echo fighters but eventually became their own rather different characters as the game series evolved.
Same with Injustice and characters like Supergirl and Power Girl or how they managed to get all four Teenage Mutant Ninja Turtles into the latest game despite them having different weapons.
Something similar could happen with common Star Wars 'template' characters like Jedi... maybe with different movesets based on their 'lightsaber style' so in theory you could have a Ki-Adi Mundi and a Count Dooku, both supposedly skilled in 'Makashi' and thus would have similar precise fencing style movesets for their lightsaber combat, but obviously different stats, and different uses of the force since one is a Jedi and the other a Dark Jedi/Sith. Someone like Asajj Ventress meanwhile might have a smaller hit box (and smaller reach but quicker base stats) while someone like the Grand Inquisitor could have less force power or abilities but some extra abilities based on the spinniness of his lightsaber design. They'd all be "echos" of the base Makashi fighter who hypothetically using your game, would be Asajj Ventress.