I know that to beat Odin you need a very damage-dealing plan, because after a while he raises his sword, which means he will be using "Zantetsuken" soon. I forget exactly what this does but I'm pretty positive is simply kills everybody.

Deal as much damage as you possibly can. I also believe that casting "Slow" on him works on slowing him down. Have Rosa cure when she can. Have Rydia cast Thunder-based spells on him.