Okay, this is very simple. Firstly see if you have the Photon Debugger keyblade ( get this from tron when you have completed his world) . If you do it well help a whole lot. Right equip to sora a load of items to increase his ability points, and make sure thunder boost its equppied as a ability as well as lucky lucky and draw. And make sure u have a lot of ether of mega-eather. Next go to the tower in Twilight town where u get the new clothes make sure your on the top level is master Yen-sid room. Once here set Goofy anbd Donalds comands to Sora attack. Whilst on the customize screen set soras to L1 + Circle to thundaga, or the highest thunder magic u got. And set the rest to ether or mega-ether depending on what u have on Sora's item list. And equp the photon debugger. Once done all this.... go to the door leading to the stairs. Once through the doors keep wlking down them until a bunch of berserkers appear, quickly change to Final form and hole L1 and keep pressing circle to cast thunder magic. You will see that it i very effective and all of them will die within about 2 casts. Once this done jst go through all the rooms doing the same thing and once at the bottom at the front door go to the save point and to world map and repeat what you have just read. If you get into the save point whilst still in final form your drive gauge will go to max when you get of the gummi.