Wow.... for a challenge i'm doing mission mode.... but i am SO using two become one as a rule bender. Xion and Roxas use Two Become one in the manga so I'm using that. (zero gear w 2 ability units). Anything lower in power is waaaaaaaaaaay too hard!
Try this: Mission: 89: Eliminate all 7 giant heartless in MISSION MODE!!!
Equipped: YOU MUST HAVE BLOCK (4) with Bonus block, round block and auto-block (this is a must if you want to complete the mission
Restrictions: YOU MUST KILL THE DUSTFLIER!!!!
more help: Roxas as DW has been sharply lowered in attack and you won't get enough time to dodge attacks. DON'T use him.