Domino vs Mistique vs Black Widow

All skilled fighters with unique abilities, no prep, each have guns, chemical factory, no morals

If this is a curbstomp PLEASE tell me

Not at all, but I got a feeling Black Widow is the most lethal with a pistol. Although, Domino's power makes it difficult to decide a winner, cause her power could potentially allow her to win.

Domino.

I lean toward Domino as well. I think all 3 have a decent shot for the win base on fighting skills and skills with weapons but Domino's probability manipulation could tip the scales in her favor.

I think Domino wins due to luck powers.

I am leaning towards Mystique or Black Widow or Domino... hmmm... 
 
Mystique is not your regular villain she has her tactical skills and shifting capabilities making her not an easy target. 
 
Black Widow is a mistress of stealth and tactical skills. 
 
Domino has tactical skills and a power of luck (that isn't a guarantee all of the time). 
 
I still need to think this one through.

Domino. Probability manipulation FTW.