Translation of the trailer:
The heroes stand on a cliff
Cloud of Darkness: I waited after awakening to make all despair.
Onion Knight: I won't let you erase anything.
Onion Knight: I discovered the power to protect everyone!
Tidus: So that was the reason you and the others joined.
Tidus: And this, is mine….!
Squall: Leave that behind.
Cloud of Darkness: Why can't I destroy it?
Cloud of Darkness: It's just a fragile living thing.
Kefka: Play carefully now.
Kefka: She is an important friend of mine.
Sephiroth: I'll work to see you despair.
Sephiroth: Because you are... a puppet.
Warrior of Light: When fighting against true despair, you'll know the answer.
Kuja: I'm addicted to scheming?
Kuja: When you know nothing, there is nothing to scorn!
(Idiom equivalent to "Ignorance is bliss"?)
Garland: Battle is an endless cycle!
Jecht: You showed up.
Tidus: You're being deceived!
Tidus: If you can cross over, then come tomorrow!
Jecht: So stubborn. Who do you get that from?
Tidus: It's decided then!
Cloud of Darkness: The time has come, everything is ripe. The final struggle to the death.
Emperor: If there is a perfect (blank) to possess, it is all up to the whims of the gods.
(Yui-san forgot one of the words which is why there is a blank)
The Warriors of Chaos gather around the magma...
Source: http://community.livejournal.com/ffchaoticcosmos/
Oh and the source of the other info is somewhere on NeoGaf but I don't feel like looking through hundreds of posts for it again, but it is legit.