Yes The D-Pad

ok imma give you the methods i use and it should work!
1: Know your fatality!!!! (most important)
Make sure you practice doing it a few times before you try it...just pause it as soon as it says finish him/her
2: Makes sure you go into fatality stance by tapping the L-Trigger when it says finish him/her!!
3: Speed and timming is real important...make sure you dont panic and do it to fast...they provid lots of time to preform the fatalitys now!! dont do it to fast but dont do it to slow!!...ya get me?
4: make sure you hit the last direction of the fatality and the botton at the same,time this really helps!
5: Know your distance! IF a fatality is marked Sweep....get all the way up to you victum and jump back ONE TIME!(thats sweep distance)
When a Fatality is mark Close, Try doing it all the way up aginst your opponent...if that doent work try taking ONE STEP back
When a Fatality is marked Far Try jumpng back TWO OR THREE TIMES then try it!
i hope this helps because i know how confusing it can get!!

well i have a website that can help with that in the faitality section.