1. Tag functions built into the engine
I feel that it would benefit to just have a SCTRL of this rather than have to fiddle around with uno tag (even though it's pretty good as it is) and such. Maybe have options upon how the tag works like is it following tekken tag rules, (when a character gets KOed the team loses the round rather than the partner coming out) are the characters jumping in or running in, can they attack while tagging, do they have to be in a specific spot to tag in (Like Kizuna Encounter
https://youtu.be/U77h27eSa8U?t=15s), etc.
2. Offical 3v3 and 4v4 simul support
Even though I am not a fan of this mode, plenty of people are and it would bring attraction towards this engine just becuase of that. Stages would have to have their own p3 and p4 triggers repectivly. (like p3startx = , p4startx =, etc) You could also apply this to the tag fuction above.
3. Stage intros and stage fx
Now i've seen that sounds are going to be introduced but not sure if I saw mention of stage intros. Plenty of fighting games have this and one example I can think up of is any stage in KoF95, one example would be is garou stage where they jump into the foreground
https://youtu.be/lTMwD9ybSAQ?t=9m2s . Also on that stage the characters have landing dust (rather water splashing) applied to them which would be cool for stages that look better with it. Also having options whether the fx add to the ones on the character, or override the ones on the character already.
4. Make it so randomselect does not pick the same character twice
Pretty self explanitory, becuase it's really annoying seeing mugen pick the exact same two characters by the same author on the same team.
5. Reimplmentation of the learning AI feature that mugen has
If you've ever wondered what the ai = farts.ai file in characters def files where, from what I remeber are for a self learning AI feature that was never implmented fully though still has some effect albeit not much. Not sure what the files are coded under though I think you where able to "train" the AI by doing combos withing training mode and saving it to the character. Not sure if I'm 100% accuracte with what I said but that's what I can remeber.
6. Character croping SCTRL
Pretty much an SCTRL to allow cropping of sprites which an obvious benefit would be mortal kombat characters with fatalites on oppoents which with a cropping SCTRL would allow them to do on anybody withot the need for any custom sprites.
7. Down system
What I mean with this is in such games such a JJBA:HFTF when the characters lost a round they didn't get KOed and just fell down for a second and got right back up for the next round
https://youtu.be/4i6J9UjRYbk?t=49s