How do you beat Ansem after you beat the Darkside in Kingdom Hearts 1

Name: Ansem (Xenahort's Heartless) and Guardian
HP: 1200
Exp: 20,000
OK, he will start with one of his basic attacks from your first battle. He will fire a underground laser at you.That is phase 1. Phase 2 is when he starts to use his possessing attack and a homing missile attack. Phase 3 is when he uses Guardian heartless to attack you from underground. Simply just dodge roll in circles till he says "The final darkness is now". Dodge roll even if he says that to avoid his attack. Congrats! You just reach the half point mark! Yes, there are two more Ansem battles left. One alone and one with your allies.
Tip: When he possesses you, DON'T ATTACK! It'll freeze you in place, and you'll very likely die.
Reminder: Battles 3 and 4 are pretty easy. Just make sure you have Aero (Aeroa or Aeroga) on and attack a crapload! He will die faster in no time! Hoped I helped! =)