Yeah, I seriously doubt that Liu Kang defeated Shinnok. Shinnok was too powerful for Liu Kang to have beaten him. I would either go with Raiden or Quan Chi. Note that Quan Chi could have been dragged to the Netherrealm AFTER Shinnok was defeated. Seeing that Quen Chi still has the amulet, I think it's more likely that he defeated Shinnok but then found himself in the Netherrealm before he could conquer the realms.

I am still not sure, however, if Shinnok is still alive or not. Was he killed at the end of Mortal Kombat 4 or banished again to the Netherrealm? Seeing that Shinnok didn't seek revenge on Quan Chi while in the Netherrealm, I think he might have died... but that's just a logical guess.

Shinnok could still be alive. The first time he was banished to the Netherealm he was imprisoned and tortured there until Quan Chi helped him escape from his prison. When you defeat him in the end there is a earthquake, his head spikes up, turns into a bloody skull, falls into a blue tunnel which I am guessing is a portal and finally disapears into a some kind of fire ball which may be the portals exit into the Netherealm. Personal opinion of mine is that he is still alive but imprisoned and tortured again unless someone wants to give him a hand again.

Who ever killed him is my new fav character.

Midway said that he was killed off for good. Not banbished back to the Netherealm.

Shinnok was one of the best characters in MK4
it sucks to know Shinnok is dead