Add: Third kits for every weapon, starting with weapons that didn't get third kits in Splatoon 2
I don't think narrow kits that follow the A/B formula should exist anymore, I'd prefer a "custom" kit system where a weapon has A1/A2/A3c and B1/B2/B3c pre-determined options the player can mix/match [with restrictions]. So you can run A1/2 and B1/2 but you can't run A3c/B3c, only A3c/B1&or2 and such. So instead of rolling out Kits "Stickers" can be rolled out and due to "style" you can't use certain Stickers with eachother. [Perhaps for launch weapons have 2 Sub options / 1 Special?]
Adding on top of that, I love how Splatfests have Fizzbangs as a secondary sub that didn't [seemingly] draw from the inktank and granted charges based on kills. Weapons having a Secondary sub that can't be changed and is tied to its archetype would be a fun change of pace, granting potential "security" to make up for a weapons shortcomings upfront and be a another solid part of a weapons identity to keep it grounded in wake of Kit Customizing. Perhaps Angle Shooter is depreciated and is now Silly String, creating a spiral string that tracks targets with the canister exploding on player-impact.
I'd also appreciate a condensing of subs/specials, Superchump [inspite of how "bad" it is] is a balanced take on Tenta-missiles, Splashdown, Inkstrike, Booyah Bomb, etc. Or how Wavebreaker is a balanced take on a passive Area Denial special compared to the likes of Killer Wail 1&2 and Ink Storm. Ink Vac could become an alt fire mode for Ink Jet and Curling Bomb could be recondensed with Autobomb, like a lock-on roomba. Or Inkmine and Sprinker being merged, for a shorter duration sprinkler with a delayed explosion thats proximity & destruction based for example.
As for an original feature Id like to retire the current way maps are designed and the two home system. A big problem I hear from people and occasionally agreeably experience myself is Spawn Camping. A two party system with "linear" maps practically encourage spawn camping. How do you win? Gain ground. Push ground. Corner prey
A 3/4 grounds system where a "pushed" spawnpoint rotates your home grounds would solve spawn camping and allow recovery from hard pushes. A team would still have a dedicated spawn grounds and they'd share the C/D grounds, rotating between whos in the most danger at the moment and allowing some unpredictability.
I don't reckon this would make maps much bigger, perhaps wider or more horizontally mirrored maps [with 3 spawnpoints?] and it's possible the spawn thing wouldn't play good, but at the very least I'd like a new map formula. Splatoon 3 has such cool movement options with no geometry to use it on.
I've been wanting this since Splat2n and its FOAM. I think having a way to create temporary ink surfaces would be transformative for the map and ways to play. You wouldn't be able to build it up like in Foamstars, the way I see it is more like a Slip'n'slide, or a sprinkler that only covers the area within itself as an object. you can cover an enemies foam but itll foam back up slowly, covering up the ink. Itd cling onto enemies, with the chance to submerge into ink leaving the foam behind before it starts popping. itd deal low damage, like ink storm.
Fizzy Bomb could have reduced ink coverage but have foam coverage, creating a lasting lowdamage AoE fields and Burst Bomb could have reduced impact damage but leave behind foam with its detonation making up for loss impact damage. Wave Breaker could become a Foamy Wave. A unique special for this would be Foam Hose, itd ooze out foam in a stream as its mainfire and its altfire creates a foam "shield" that team mates can shoot through to convert their ink into foam! And a weapon could be the Marble Splattershot, when initially shots it creates a small spray of foam before becoming a normal ink stream.
Maps could have "hard" uninkable surfaces that are like wet walls or something, dispells the ink. Preferably limited to spawn grounds and such, splatoon 3 has too many uninkables... I can count how many walls I can paint on maps with both hands [then multiply it.]
That's all I can think of right now, I'd like to doodle out the Marble Splattershot as a marble soda gun sounds silly...