They're fighting games. Why do we need to incorporate machine learning at all? If the computer wanted to they could always play perfectly because it could react to any input perfectly.
http://www.polygon.com/2015/5/30/8691219/killer-instinct-tea...
It probably uses a hybrid or AI and scripting techniques.
As for things like human reaction limits etc, that can built into the AI as part of parameters it needs to operate within.
Not making an AI that has perfect response, but a "human-like" one.
It would make for a formidable opponent since you can still defeat it (with a good dose of luck).