Which Street Fighter II update was produced in response to bootleg editions?

The Street Fighter II update produced in response to bootleg editions was Hyper Fighting.

Street Fighter II: Hyper Fighting was Capcom’s official follow-up to Champion Edition in 1992. Unauthorized modified versions had appeared in arcades, most famously Rainbow Edition, altering character speeds, special moves, and other gameplay rules. Rather than ignore the phenomenon, Capcom incorporated some of the demand for faster, more chaotic play into an official release.

Hyper Fighting increased the game’s overall speed and gave several characters new or modified techniques. It also changed costume colors and refined the balance, making it a distinct competitive revision rather than merely a security response. In Japan, the arcade game was titled Street Fighter II Dash Turbo; overseas, “Hyper Fighting” became the familiar name.

Players sometimes confuse this title with Street Fighter II Turbo, the Super NES version. They are closely related: the console release adapted the Hyper Fighting update but used “Turbo” in its title. Champion Edition came before it, while Super Street Fighter II followed with new characters and a hardware change.