What gimmicks that haven't been done in characters/2d fighters in general yet?

[Artoria Alter]

I'm curious, because surely there has to be some untapped potential.

[SSBKing65✯]

The Superguard, in PM:TTYD if you pressed B right when you were about to be attacked, you'd deal 1 damage back to your enemy, and deflect their attack, that wouldn't be difficult at all to do and it's only been in that game.

[Big Green]

This is possibly impossible to replicate, but the concept of knocking characters into another scene a la Clayfighter 63 1/3 and Dragon Ball Z Hyper Dimension.

[Luis]

The clashing from The Queen of Heart 99? When two attacks collide they will clash and who ever wins will take a lot of damage. It's similar to the clashing from Arcana Heart.

[TMC55]

Free for All, like in smash bros when every character on the stage fight each other. It would be pretty cool. I think I seen it on a smash bros version of mugen but it would be cool to see in regular mugen

[Demitri]

This is possibly impossible to replicate, but the concept of knocking characters into another scene a la Clayfighter 63 1/3 and Dragon Ball Z Hyper Dimension.

Not impossible but not worth the effort outside of a fullgame. ELECTR0 has actually pulled this off not too long ago, and SyN scratched the surface of this many years ago(replicating the battle area changing from MKvsSF 3). I say scratched the surface because the arena change was forced.

[SSBKing65✯]

There's a special type of block in KH 358/2 Days that give the enemy status effects like Blizzard Block, and Thunder Block, but it'd only work sometimes. Your foe would be frozen or jolted like in the game, it'd be interesting to see it implemented in Mugen.