Make sure to beat the 2 misson to do this
First equip your gullwing if you dont have it then look for yuna riku and pain in hallolow bastain then go to pride rock go in the kings house and go all the way up top of pride rock There will be millons of heartless attack you well not a millon just a lot of heartless kill all the heartless and you just got at less 20,000 exp there mybe more or less but do this a lot and you'll lvl up fast^^
First equip your gullwing if you dont have it then look for yuna riku and pain in hallolow bastain then go to pride rock go in the kings house and go all the way up top of pride rock There will be millons of heartless attack you well not a millon just a lot of heartless kill all the heartless and you just got at less 20,000 exp there mybe more or less but do this a lot and you'll lvl up fast^^