Some suggestions.

I know it's a bug (seen it often in source game vids) but sometimes Ken gets a invisible Energy Ball that instantly hits p2. It's not a frame rate issue, after all the Energy Ball does not travel, it hits straight away. Dunno if you wanna implement it in one way or another into your version of Ken. Maybe a "just frame", hard to do version of his Energy Ball? Maybe is invisble, maybe travels faster, but should be blockable?

Another glitch/bug I could replicate in the emulated version. Because of the atrocious controlls, the specials are hard to do and you mash the commands to get them to work. Sometimes you can ko p2 with a Energy Ball and in the next round Ken does the Energy Ball again, even before the round starts, but away from p2.
Have seen it in a vid, then I tried it in the emulated version.

You could use that a as another win animation or a intro.