How the hell am I supposed to beat this guy?! Every time I get him down to almost no health he blasts us away and gets all his HP back.  
 
My guys are way overpowered for this area so it's not hard getting his health down (at all) it's just that I don't know how to finish him.

Just level up more, it'll make everything go much smoother

" Just level up more, it'll make everything go much smoother "

I'm not that far yet, but maybe you can stagger and launch him?  Then time your attacks to keep him juggled so he can't get his attack off?

Who here saw Final Fantasy Gil Quest?

Tonberries have been a pain in the ass throughout the entire franchise.  Its not just FF XIII

"

SPOILER WARNING: Click here to reveal hidden content.

I see you single tonberry and raise you a fight with 3 at once, good times.

"

I beat one quite easily yesterday with my party of light, hope, and snow. Just get buffed up and start to work on the chain as fast as possible. Maybe you could try a com/syn/rav and switch to com/med/rav just to get healed up. I went with triple ravs once I was ready and didn't waste time healing for the rest of the battle. I'm not sure if I ended up staggering him, and I might have changed to com/rav/com once the chain was fairly high to finish him off. If you're able to stagger and launch him then I assume he won't be able to heal back up, but he didn't heal when I was fighting him anyway.
 
I'm pretty sure i did it under 2 mins, and certainly got 5 stars for the mission.

whos tonberry?

" whos tonberry? "

If it's the mission with 3 of them, make sure you get a preemp strike, then just ruinga them so they're all staggered then go at them. I went with two commandos and a rav, so one com would be beating up the second while the rav and other com made quick work of the first then moved on to the third.
 
When it comes to the single tonberry one, I went tripple rav to get it staggered fast, then switched to com com rav and beat him to a pulp while juggling him.
 
Oh and if all else fails -- Lucky Strike. Equip both sashes and you'll get a chance to instantly fill the stagger gauge. This is pure luck, but if nothing else is working it's certainly worth a shot (and the easiest way to beat some of the more frustrating missions like the Neochu with adds)