I recall hearing of a "Rakuga Kids" which didn't get a release in the USA.
Also, the N64 had the Mortal Kombat Trilogy game.
I think that for some reason devvers were put off on the idea of making 2D N64 Fighters for some reason - in comparison, there were more (mostly shoddy and forgettable compared to Saturn or Playstation ones) 3D fighters. Possibly just people jumped on the "2D is dead" bandwagon (and Capcom didn't jump on N64 until near the tail-end of it's lifespan, and just released Playstation ports on it.)
As for the Sega CD doing Alpha 2 - I do not really think it'd have been that easy. The Sega CD's power didn't seem to do much for improving NeoGeo ports over their Genesis originals, after all. And the Sega CD by itself didn't add additional color to the system.
That being said, other give the Sega CD much of anything after "Final Fight" was ported? In a way, it's kinda sad wondering how a Street Fighter port might've worked on the CD System, only for it to not happen