Kingdom Hearts HD 1.5 + 2.5 ReMIX - Final Mix - Phantom Heartless (Strategy in Description)
0A quick run of the phantom.
Strategy:
Basically as the fight starts you'll want to cast Stopra on the clock and you should come back to cast it again periodically throughout the fight (about every 30 seconds or so), this will stop the timer above Peter Pan's head from counting down.
As for the Phantom, he isn't too much trouble, every so often he will have a heart showing from under the cloak which will change colour and each colour indicated what you have to do:
White - Physical Attack
Red - Firaga
Blue - Blizzaga
Yellow - Thundaga
(I also recommend equipping accessories that have high MP and Mega Ethers)
If I recall he only really has two attacks you need to keep an eye out for, one where he'll come up and slash at you (just fly away from this) and one where he shoots a purple homing attack at you (again just fly away, also having Aeroga cast just before he fires it is really helpful)
Just repeat this process, be swift in your actions and remember to keep the clock stopped and he should be down within minutes.