What is the best strategy to defeat Cid Raines?
I found party composition to be a major MAJOR issue with fighting Cid. I tried it at first with Hope, Vanille and Lightning and Cid mopped the floor with me. I tried again with Lighting, Fang and Sazh and had much better luck. Standard assault paradigm with Com/Rav/Rav, but be sure to have a medical paradigm to heal, and BE SURE to make use of Fang's saboteur skills and Sazh's synergist skills. Those alone should make the fight super easy. I beat him in like (seriously) less than 7 minutes.
Suggested paradigms are:
L-Lightning, F-Fang, S-Sazh
L-Rav F-Com S-Rav :: L-Med F-Sab S-Syn :: L-Med F-Sen S-Syn
Those three are paramount, everything else is gravy. If you've given Sazh any medic skills a fourth paradigm with L and S as medics and F as a sentinel would be helpful for those Oh ****! moments.
Personally, I did not change my tactics for Cid, but that did make him a very tough fight that took me a few attempts to win.
My regular tactic was to use COM/RAV/RAV to raise the stagger gauge and then RAV/RAV/RAV while the enemy was staggered to do as much damage as possible, with a MED paradigm thrown in for healing.
However, in the fight I managed to win, I did have to use potions a couple of times to heal and I lucked out as he concentrated most of his firepower on my teammates instead of me. When they died, I summoned Lightning's Eidolon, which revived my party and allowed me to finish the fight.
You may also want to review the strategies here, to see if those help you out.