The game can be No Crystarium'd until Balthandras, so by using a better strategy, you can win this. Learning to optima change quickly in battle really helps you, you also need to know the bonuses that come with it. What I do is start the battle with Hope as Enhancer and Lightning as Attacker. I use Scan a few times or I use a Libra Scope to reveal the elemental weakness. You could look at its color, but if you have the Scan data unlocked, the other characters' AI change and always use Super Effective moves. After all of the positive statuses are up, I switch to Attacker/Blaster to steadily increase the Break Gauge. If you don't already know, Blaster attacks raise the gauge quickly but cause it to fall quickly, Attacker attacks raise the gauge slowly but also stop deterioration. So using both will increase the gauge a lot. Once it's Break'd, just chain it to oblivion. If you get low on HP, throw a few potions or switch to Attacker/Healer.
I don't think Lightning and Hope have Defender at the moment, but a nice tip for the future is that whenever a large attack is coming, switch all of your party to Defenders. Just by having them in your party, you get added defense.
Oh and this boss is Bulbasaur.
Quote from Blizaga;247050:
I never even had a problem with this boss, I had a problem with that guy you fight in the airship. He's basically a giant face....
Summoning an Eidolon and going into Gestalt Mode gives you invincibility frames. :V