Okay, this is my big one i've been working on.
How to beat boss rush in Castlevania: Aria of Sorrow
Creaking Skull
If you have the Curly, Devil or Manticoe (The god souls) then this very easy. Use one of them to ram through the skeleton, them when you are on the other side then chop at his tail. His attacks will miss and he'll die easyly.
Manticore
Using a god soul, just ram the Manticore once. He's the second boss but he's actully easier than the creaking Skull. He should catch fire with one hit.
Man Eater
his boss makes no sense. In the real game, the Man eater was just a normal villian, but in boss rush he's a proper boss that get the life giving thing off of and all. Anyway, it takes 3 god sould hits per eye to kill him, so kill two then slash the last one with a sword so you don't waste MP.
Dark Knight
Use your God Soul. Once behind him, he'll turn around so use it again quickly. Repeat a few times and he'll go down.
Big Golem
This guy is actully very easy. You do the same as with the Knight but the Golem doesn't turn around so you can slash away from behind. Just remember to get out the way if he starts walking backwards.
Death
The Grim Reaper himself. Use you God Soul for part 1 because you'll hurt him but won't be hurt. When he brings out the ultimate weapon, do the same but if he trys to ram jump over him then jump once more. When he throws his weapon use the oppertunity to slash from beneath then jump. He'll break apart and get sucked into a black hole. Technically, I think you should be immortal after this as you killed Death, but game makers don't think that way.
Legion
This guy is very easy. When he comes near you, run into the corner and use the God Soul. He'll try to hurt you but instead his shell will get broken. Keep doing it and the laser snakes will die too.
The Balore
The hardest boss. Dodge his fists and stab his eye. You have to work out his pattern of fist movements to succeed. When he shoots lasers, use the medusa soul and hover by his eye. The lasers will miss and you are free to stab away.
Graham Jones
Dracula is a tough one. In wave one just duck and occasionally jump over his attacks then stab. When he becomes the monster you should slide out the way of the laser and hit him in the face. Be careful of his hands. When he dies you fight the hidden bosses.
Julius Belmont
Your friend is trying to kill you because you have become Dracula. Just use God Souls but when he rises into the air, run like hell or he'll beat the crap out of you. When he lowers himself finish him. Unlike other bosses you don't kill him as he's your friend and he only attacked you to defend your other friends.
Chaos
The final boss is quite easy. Each circle has a different attack: summon a monster, shoot triangles and bump into you. Kill the monster one first as it's the most dangerous. Then dodge the triangles and kill the other two. Ulimate Chaos is still easy. When triangles appear, run out of the way, same for the snake. Slash the circle to beat boss rush.
If you did in under 4 minutes you get the best sword in the game as a reward. Also, beat the game as Julius to play as him in boss rush. I haven't tried that, it sounds near impossible. Soma is hard enough.