Warning! Spoiler alert!!
After dozens of attempts with different parties, I've noticed the same thing in this battle and why some parties are having a hard time: People aren't moving away from the AoE fast enough and getting knocked off. The main reason is that Titan's AoEs are MUCH shorter than what we have experienced so far in the game. It's literally 2.5 seconds of error. Meaning that if you stand in the AoE for more than 2.5 seconds, you're gonna eat sh*t. Period. This is the part of the game where it forces you to pay better attention during battle. MOVE or STRAFE away from the effect.
Here's a breakdown of the fight from what I remember. Please add/correct if I'm missing something.
1st part in the fight. Titan will jump in the air and land, causing damage to the entire party. During this time move out of the yellow circle to avoid taking the most amount of damage. The entire party will take damage no matter what from this attack. Also, don't stand at the outer brim where the red is blinking. You'll get pushed off the platform and die.
2nd part: Titan will jump in the air again and but this time will have his heart exposed. It is crucial to kill the heart within a certain amount of time, otherwise he'll wipe the party. It's similar to the Ifrit fight with killing the "fetter" first. The tricky part during this phase is that he'll encase someone in stone. Get that person out ASAP! If you try to be a cowboy and continue bash away at the heart, you'll end up failing. The entire party needs to work as a team to destroy the heart in time.
Note: During this part he will cast the Landslide AoE. If you are in the BLUE PATHWAY, you gotta drop what you're doing and GET TO THA CHOPPA! Seriously, if you're a caster, stop casting and boogy! Like I mentioned above, this AoE happens very fast.
3rd part: After the heart is destroyed, he'll go ape sh*t and cause the party some damage. He'll again encase someone in stone and it's vital to free this person.
During this time a NEW AoE happens in addition to the AoE landslide: He'll cause the ground to ripple and explode. You'll have to move fast for this too because it happens very quickly and you get dealt a lot of damage if you don't move out in time.
If the party is able to survive up to this point then you are pretty much home free.
Hope this helps.
Edited, Sep 3rd 2013 1:57am by ASpaceman