I feel like many of the 236 and 214 attacks could be transferred to simple Neutrals. Perhaps converting the movesets to a more traditional ABCD arcade-style mapping system would work better? Primarily, this game has a lot of potential. Fix a few sprites here and there, work on a more custom HUD, perhaps a tutorial. With a bit more work, this game could easily be transferred from a MUGEN fighter to a completely original programming.
An example of what I meant by transferring the Neutrals and Specials would be Hideki. For example, all of his punches converted to A attacks, kicks to B, knife attacks to C, and warp attacks to the D button. As such, he'd have a few more warps, a heavier mix-up game, and the potential to become a slightly technical character. However, attacks like Carnage Onslaught (That's the anime-fighter attack name I gave to his 236X/Y/Z) would remain a Special, although mapped to the C button, his Ripper: Hori (214Y) and Ripper: Vert (214X) would be his 214/236D. And, his Manslaughter (214Z) would just be his normal backward throw. He could have a simple anti-air in which he slashes above himself in an arc, and so on and so forth. Along with that, his dash kicks would be simple 236B's (Forward kick would be 236B and upward kick would be j236B), with his followup flip kicks being 214B's (Frontflip is 214B, backflip is j214B). However, these are just a few ideas.
The next move after reworking the basic movesets would be replacing the sprites with original ones, not from the Melty Blood series. I'm assuming that Juanimo, Nami, Nishi, Utada, Toriyama, Remy Jacuzzi, and Nana Cat are original. If that's the case, then they're very well done already. This could also lead to some more original characters, each with different methods of murder. Hideki is a knife wielder, Sara has claws, Mara has a sword, Asuka has ice magic, Nishi has fire magic, Juantomino is extremely powerful, Remy has the capability to lock onto weak points, Nana Cat has memes, Nami can shapeshift, Utada is a bear, it works. However, Toriyama and Juantomino and Nishi all have similar methods of murder; so Toriyama could be given a different weapon. Perhaps a sword for his C attacks. You could even add a few more characters. A dual wielder, a spear, a gunner, a whip, so on and so forth.
In short, you seem to have limited yourselves to minimal capability per button rather than venturing into more traditional and fun territories with the simple numpad notations. My recommendation would be to step outside the box and not restrict yourselves to MUGEN's rather conservative layout.
Lastly, I know this is a bit of a big request, but I'd be glad to assist you with the development of ARCADE DREAMS: Blodbath in future if that would be okay. I actually came up with a few ideas as for expanding the movesets of some characters.
Sincerely, your fellow developer, Okeirany.