Ok,this is it.I am finally at the end of this game and the only thing stopping me from getting it is Ultimecia

For the people who have beaten her please give me all of the advice that you can.However keep in mind that my party is at leval 40 and I dont have a lot of fancy items to use.I have a couple of questions concerning the fight though.

1.Someone told me to cast Meltdown on her,but do I just cast it once or do I keep casting it.

2.Is there anything in particular that I should junction to my party when I fight her?

Those are my biggest questions so if anyone can help me I would really appreciate it.Thanks