In case you didn’t notice, the graphics and sprite sizes for all of the 16-Bit SFII ports (that includes SNES, Genesis, PC Engine and even Game Boy Advance) are all identical, and originate from the SNES ports of WW and Turbo. As a matter of fact, “Special Champion Edition” for the Genesis WAS ported from the SNES Turbo, a job done in the last 2-3 months before the game was due to be released.
Originally, the Genesis was to receive a port of CE that, while inspired by the SNES’ SFII ports and their way of scaling down the original coin-op’s graphics, was to be a port made from the ground up for the Genesis hardware. For those of you who read and followed gaming magazines circa early-mid 1993 (especially EGM & GamePro), this “early” Genesis SFII port is most infamous for having slightly smaller sprites than even the SNES WW, and ugly black borders over the life bars that cropped even more of the screen. The latter problem was fixed in the latest revisions of this port (from around May/June 1993), one of which has long been available over the 'net as a “Street Fighter II Turbo” ROM for the Genesis, or as presented in the title screen, “SFII Turbo”. And if anyone’s played this ROM, then you’ll also notice that this canned port contains noticeably more character animation than all the other 16-Bit SFII ports (yet still not quite CPS1 quality), and instrumentation very similar to the original CPS1 coin-op (killer drums and FM-synth guitar!), along with the sped-up “near death” music missing from EVERY OTHER 16-Bit port of SFII. Oh yeah, slightly better voice samples than “Special Laryngitis Edition” as well, yet still not as good as the SNES/PCE ports.
It appears that, between the period of May/June 1993, which is the farthest this Genesis port of SFII was developed, and September/October 1993, when SCE was released, that Sega or Capcom decided to scrap the first port entirely and simply port over the recently-completed SNES port of Turbo, hence why aside from cart size, color palette, screen resolution, sound quality and a few redundant animations they look the same. Same with the earlier PC Engine port of CE, and same with the two ports of vanilla SSF2 (which were said to have bombed at retail due to overestimated demand and production on Capcom’s part, though the SNES port did sell 2 Mil worldwide). Here’s some videos comparing the earlier, CE-based Genesis SFII port, and the later “Special Champion Edition”:
Turbo (technically Champion Edition,Genesis):
Special Champion Edition (Genesis):
I assume that most who had the money springed for the Panasonic 3DO port of Super Turbo, released a couple of months after those redundant SSF2 ports (truth is, both 16-Bit consoles’ cart size limits were more than maxed out, as was their hardware. I imagine those shadow trails would’ve wreaked havoc in the form of slowdown and flicker on 16-Bit ports of ST, look at how the GBA port slowed down and required the life/super bars to disappear off-screen!) and never looked back.