And speaking of Julius, his boss battle from Aria of Sorrow is considered one of the series' high points. Special mention goes to the second phase of the fight in which he starts using Grand Cross, which not only does MASSIVE damage and pull Soma towards it, but actually causes Dracula's Castle to crumble apart in the background.
Dawn of Sorrow has a few awesome moments.
After Dmitri spontaneously dies during his battle with Soma, and his soul is absorbed by Soma, he later is released and possesses a doppleganger to gain a new body. He then explains he did it so he could touch Soma's soul and copy the power of dominance.
When Soma meets Dario Bossi for their second fight. Dario has fused with a powerful fire demon to become insanely powerful. Soma tells him "I will show you why you can't be the new dark lord." He then (if you're going for the good ending) proceeds to go inside the mirror to defeat the fire demon Aguni, completely removing all of Dario's power. Owned.
Of course, there's also the worst ending, where Soma goes along with the villain's plan and becomes the new dark lord. She starts to give a Bond villain speech about how she's won and he's done exactly as she wanted, and he tells her to shut up and kills her.
From Order of Ecclesia. In the Lighthouse level, Shanoa is chased all the way to the top of the lighthouse by a giant crab that just won't die. There's nothing at the top but a big elevator and, of course, nowhere left to run. So what does she do? Jump in the elevator and toss a one-liner. The elevator then proceeds to drop down to the bottom, taking the crab with it, with massive amounts of blood spraying in all directions before finally crushing the boss into paste. Considering this is one of the more annoying bosses for new players, this probably got a bit of a HELL YEAH.
Play Albus mode and he throws a one-liner of his own when he flips the switch.
Shanoa got her real CMOA upon reaching the castle:
Shanoa:I am the morning sun, come to vanquish this horrible night! (Also a Shout-Out back to Simon's Quest)
Especially considering everything that happened before. She lost most of her friends, found out the true reason for Ecclesia, and found out that she was a Tyke Bomb. Then she finally reaches Castlevania and prepares to finish her mission while her theme, An Empty Tome plays in the background.
The Final Boss fight with Dracula. First, he has no One-Winged Angel form; instead, he just goes polygonal, walks around, and beats the crap out of you. Second, instead of having 6666 HP like he usually does, he instead has 9999 of it.
Shanoa, not a Belmont or even alllied with any holy powers at all, losing everything she has in the world and still kicking Dracula's ass WITH HIS OWN POWER.
Then, from Aria of Sorrow: If you have a certain set of souls equipped when you fight Graham (the fake final boss), the powers Graham was trying to harness flow into you... and YOU... BECOME... DRACULA!! Then you get to fight Julius Belmont.
Portrait of Ruin. You walk into 13th Street. A train comes at you at top speed? Do you run? Yes. You run RIGHT INTO IT AND STOP IT WITH YOUR BARE HANDS.
Also from Portrait of Ruin, the Final Boss. For the only time in the series, Dracula and Death fight together against Jonathan and Charlotte! Death covers the top space of the room and if you happen to be under him, he will dash downwards to get you. Dracula keeps this up by using his normal Teleport Spam and Hellfire/Dark Inferno spells to whack you from the sides, forcing you to multitask between Dracula and Death. Oh, and you think you're the only one with dual crushes? If the battle goes off long enough, Dracula and Death show off a few of their own! First, Death and Dracula will wall you into one side of the room before Dracula turns into a swarm of bats to kill you. Second, Death will create a horde of his sickles on one side of the room. Think you're safe near or far from them? Think again: Dracula absorbs them and throws back out a flurry of Dark Infernos! Finally, Death transforms himself into a huge scythe, which Dracula proceeds to GRAB and slam down on the ground to unleash his Demonic Meggido attack! But wait, there's more! When taken down, Dracula uses Soul Steal to take Death's power for himself and becoming a new bat monstrosity that can unleash hellfire from above and try to crush you between his claw wings! What Charlotte says at the end of this fight truly captures how it goes: "That was a wonderful display of impromtu teamwork."
Fans prayed it'd happen one day, and despite the fears of Konami blockading the dream, it has finally happened: SIMON LASHES OUT!