There are 5 bosses in this stage, and may I say some of them are hard! First boss is Riku. Sure you didn't have your keyblade. And sure you didn't have Donald or Goofy in your party, but you will get all that in one simple battle. Now Riku is pretty powerful, especially if you don't have the right keyblade. Have Olympia keychain on you and have mega-potions and hi-potions on you and your teammates. Okay Riky is very, very fast. So jump or use dodge roll to evade his attacks. You want to have counterattack and Ars Ancr. on you so you can inflict more damage in less time. If you lose your health consume an ether, attack Riku, or just forget about the Ars Ancr. and focus on using the MP on health spells and aero spells. Once you do all these and repeat it you will for surely win. The next boss is Maleficent. Now she is one wicked sorceress and she also summons! Use Ars Ancr. on her or her platform, or better yet, use gravity on the platform so it will decend right away. When you get on her platform, she will try to knock you off with her staff and her meteor attack. When she's taken too much damage, her platform will rise again, she will turn into a little blackish, greenish ball and if you're on the platform it will spin around until you fall off, but you don't have to be knocked off, you can jump to stay on the platform, but it will move so think of using the glide to get back on. Don't worry about the summons she summons, unless you're low on MP, but it will take an advantage, because if she moves to the other end of the room, a storm will rise above her head and lightning bolts will hit you and your allies. Just read this until you understand it and you can beat her. The next boss, Riku [or Ansem] turns Maleficent into a dragon, and let me tell ya, it's not a pretty sight! Okay when the battle begins jump or glide on the beasts back and use Strike Raid and attack it until it says judgement, now this move may not work, but use it more frequently and it will eventually appear. When it knocks you off you have about 4 moves that it does to look out for. First, it jumps up and slaps it's tail around the place, to evade this attack you can go out to the pipes and stay there until it stops. The next attack is it shoots out green flames from its mouth all around it. To evade this attack and attack it at the same time, go to the pipes and use the glide ability on it's back or in front of it. The third new attack is that when it shoots little green, floating flames from it's mouth and the flames come after you! I'm sorry but I haven't figured out a way to evade this attack. And the last attack is when it moves around it makes big earthquakes around it. Just jump up and keep doing it until it stops. Just consume an ether or an elixer depending on your case. And repeat this process until you've won. Now it's time to take on the possesed Riku, and the person possesing him is.......Ansem! The only advantages in this battle is that, one you're alone, and second, he has 1 new attack. Riku is pretty easy except for one ecseption his new attack. His new attack is when he zooms across the platform like 10 times. So use aerora and jump then glide to dodge it. At the end of the move little lightning bolts come from four ends. Just follow the process up here and the process on Riku one and you'll win easily. The last boss in Hollow Bastion is the Behemoth. It's very easy to beat it because all you do is jump on it's back and attack it's horn. but if it thinks it's taken to much damage it will be impossible to attack at until the bolts of lightning come down and hit you no matter what you do. And there's little spheres that it sends out. Just keep attacking it's horn and you've won. For winning this battle you get the Omega Arts ring.