Should have made it Shinnok. He could kill Sephiroth with a thought, a la Reptile's ending in MK4. Outside of the restraints of the MK fights, beings like Shinnok are uber..
MAD
MadMelHeh
dont forget people like raiden and scorpian.. raiden can go toe to toe with shinnok, and scorpian is..scorpian..nuff said
NIK
NikkolasRestricted
Scorpion also succeeded where the combined forces and powers of Shang Tsung, Quan Chi and Raiden and finally Raiden's nuke suicide attack failed - he defeated Onaga.