Since when did Bison's psycho power become universally purple?

Remember how in SF II it would change colors along with his outfit? Now it’s just always purple. It makes him look boring. What gives?


It started to become consistently purple by the time the Alpha series came around.

Sf2 animated movie started it. CvS was the final transition. It was colorful in EX and it was bluish in Alpha. It was colorful in the V cartoon series.

It still changes colors. Bison can be seen with a red aura at times, and it can also be white hot.

The SNH which is at the same end of the chi spectrum is also purple.