The animation varies depending on who is Player 1/2 initiates the conversation.

If Quan Chi is the initiator, he rides up on the horse. If he responds, he walks out of the portal holding Moloch's head.
This has been seen before. With D'Vorah, her initiator intro has her fly into the arena, while her reaction has her walk in and jab her stingers at the opponent, for example.

That's possible. Strangely, it seems the P1 side frequently gets the introductory animation versus the responsive one.

I much prefer the horse. I hope he has both as having one intro all the time would be boring, but if I had to choose I would go for the horse intro. The Moloch one is "cute' but nothing special.

Actually, the intro shown depends on whether Quan Chi speaks first or second.

Why? Because I've seen the same intro on both sides of the screen for Kano, I believe.

The first speaker gets two lines - one to initiate conversation and one to end it. The second speaker gets a line in between speaker one's lines.

So with the horse intro, Quan Chi says a line while he gets off the horse, then says his second line as he makes the horse disappear.

With the Moloch intro, Quan Chi says his one line as he throws the head away.

So that's what decides the intro used, but we don't know what decides whether he speaks first or second. Seems to be random.

Yup, who is the opener of the conversation seems to be random, though the point still stands that each character has an opener and a receiver animation.

All characters seem to have at least 2 (as opener and receiver) dialogues against each other character in the roster so no matter the match, you could see any of those animation. Sub-Zero and Scorpion I think already have 4 or 5 reported dialogues between them!

Molochs head and the horse are random as hell lol. I think the dialogue will be different depending on the character more so than the intro animations. More the merrier I say.

Hopefully Quan has both.

This has been answered by the development team several times.

And that's why I apologized in advance, because I only check here maybe once a month and I hadn't seen or heard anything about it.

Thank you to the fellas that answered the question.