When can I do fatalities

[FlareGun]

so far I've only been able to do Sonya against Kano, when do I get to do one again? Also when is 1v1 online coming?

 

[SneakyTortoise]

You can do a fatality any time you beat someone...

 

[Doctor Future]

Right now, the only time is during the boss battles.

So far its:

Kano
Reptile
Kung Jin
Ermac

I think.

But once the online matches start, you'll be able to do them more frequently, when you win.

 

[killajd82]

so far I've only been able to do Sonya against Kano, when do I get to do one again? Also when is 1v1 online coming?

Only against characters that say "Boss" before there name.