These are the fatalities I know so far in MK2:
Liu Kang:
Dragon Food: D, F, B, B, HK (Close)
Kung Lao:
Body Slice: F, F, F, LK (Sweep)
Hat Decapitation: Hold LP, then B, F and release LP. You have to aim for the right spot for the head to come off. (Far)
Johnny Cage:
Torso Rip: D, D, F, F, LP (Close)
Uppercut Decapitation: F, F, D, U (Close)
-Triple Uppercut Decapitation: At right moment of impact, D+LP+LK
Reptile:
Head Eat: B, B, D, LP (Half Screen)
Sub-Zero:
Deep Freeze: F, F, D, HK (Sweep) (You can use this to reset the fatality timer)
-Shattering Uppercut: F, D, F, F, HP (Close)
Ice Grenade: Hold LP, then B, B, D, F and release LP (Far)
Jax:
Arm Rip: Tap Block 3 times, then press LP (Sweep)
Mileena:
Killer Sais: F, B, F, LP (Close)
Suck It In and Spit It Out: Hold HK for 3 secs. and then release. (Close)
Scorpion:
Spear Slice: Hold HP, then D, F, F, F and release HP. (Close)
Flame Breath: Hold Block, then U, U, U, HP (Sweep)
Special Flame Breath: Hold Block, then D, D, U, U, HP (Anywhere)
Raiden:
Explosive Uppercut: Hold HP for 7 secs. and then release (Close)
Electrocution: Hold LK for 3 secs. and then release. When the shocking begins, immediately repeatedly press Block+LK until the victim blows up.
Here you go!