I'm going to say Cazzigno kills them.
I mean Child Rydia & Edward vs. Tellah, Parom and Porum? Not even close.

Lets try to spin a happy happier ending:
- They fight Cazzigno, unfortunately he is weak to the dark sword and gets killed.
- They get the airship
- Golbez doesn't consider sending Cecil to get the crystal because he didn't see his potential as turning inot a paladin.
- While Golbez and Barbricia go kick the crap out of the Dark Elf Cecil and co. sneak into the tower of Zot, knock Kain out and drag him back to the airship. They also get Rosa back. Edward trips and kills himself because he is such a wuss, freeing up party space for Rosa & Kain. They also steal the other three crystals back. EDIT: Forgot about Cid. He goes back to Baron to work on a new airfleet to fight Golbez.
- The party decides to head to Mysidia to learn more about the crystals.
- Once there the elder tells him about the trial of mount ordeal he must overcome. He sends Parom & Porum with him like before. Kain comes too because they are BFFs. Rydia and Rosa stay to learn more, and Yang stays because they need an empty party spot for Tellah.
- Once on Mt. Ordeal they meet Tellah (surprise!)
- Mallon decides he has no hope of taking them on with Kain along with the original party. He sends waves of zombies to wear them down first.
- The mages stay outside to hold off the zombies while Kain and Cecil continue inside. Golbez assumes control of Kain once again and takes Cecil unawares. As he is about to finish Cecil off Kluya's spirit intervenes, transforming Cecil into a Paladin and completely removing Golbez's control from Kain.
- Outside Mallon has decided to engage the three mages, as he knows Kain has Cecil occupied. Just as he is about to overwhelm them the twins cast a massive twin spell, destroying the mountain side containing both them and Mallon.
- Cain emerges carrying an unconscious Cecil and finds only Tellah and signs of massive devastation.

Whew..., that one got away from me a little bit. Maybe I should take some time to think through were I am going with all of this
Stay tuned for Ch2...