I did this battle with my three mains, Ash Vaan and Basche and had virtually no trouble, maybe I can help you out.
Nihopoloa + Remedy = Will always be a surefire way to aid in a losing situation. I'm know factually Cid isn't susceptible to alot of things, but what you can do to him is there to be done because its a hinderance to him. Allright, now. Focus on ONE ROOK. Manually command Vaan and Basche to kill ONE ROOK at a time. Ashe will be busy with Ally - Basche(more than likely he has the most HP) under 50% HP. They'll target Ashe and Vaan more frequently due to them being weaker, but they can last until Basche has hit that mark. Use CuraJA. It's not much more MP than Ga, and will heal your whole party to max. When you can though (when all characters have 80+) HP, manually control Ashe to attack the rook/s you're focusing on. They're easier to kill if you take them out one by one.
To ensure Ashe isn't taking much damage (she isn't the party leader for me, but this doesn't much matter), have her kite. If you're unfamiliar with that means, just in case, it means have her run circles around Cid and his rooks.
---BTW, you don't have to use my party, but I find Swords/Spears to be more effective than Balthier's Guns, Fran's Bows and Penelo's Daggers. Having a Zodiac Spear doesn't hurt, just so you know. You should invest on increasing MP to max and getting all Quickenings, this is not hard to do in Mosphoran Highwaste due to the Humbaba's/Wolf Thingies, you will gain alot of EXP/LP (especially if you're a Embroidered Tippet/Golden Amulet fan like myself.)
Don't get me wrong, Cid is tough, he's a major boss of FFXII. Using stat boosters like Shell/Protect and Haste will help you alot. Bubble isn't a bad idea and if you're like me even more so, you use Basche solely for brute strength... SO BERSERK HIM! It may be a good idea to use Lure as well, cast it, again, on your tankest of tankers and let him take the damage, and then manually cure him. There are ways around this battle, you just need to know when its time to manually step in to get the right commands in, and you also need to know when its time to retreat your party to use stat boosters.
Cid will eventually fall to the might of repetitive brute force. I was Level 41 with all characters, if memory serves. BUT, I also wore Golden Amulets and had the whole upper right license board mastered save for some spells and techniks. If my way fails, then you may have to backtrack and get some Elixers, and go on a Quickening frenzy. Good luck. :-)
