Anti-Climax Boss: Some consider Dracula's One-Winged Angel from the first game to be this, since all it does is jump around and breathe fire at you (in other Castlevania games, it would at least fire projectiles while jumping!)
Game Breaker: Maria either counts as this or as an Easy mode. She's faster than Richter, she has a double jump, her jumps are much easier to control, she can throw two doves at the same time, which can hit the enemy up to twice, she can slide, she is slightly smaller than Richter, which makes a notable difference when you want to dodge certain attacks, and her sub-weapons, although different, can be just as deadly as (If not deadlier than) Richter's when used well. Her ending can definitely count as Easy-Mode Mockery though, as it's far less serious and far more cutesy than Richter's ending.
Stage 3' has Bottomless Pits with disembodied hands. Fall into one, and you get to hear your character scream as they get pulled in.
Despite the game's fairly bright atmosphere and 90's anime style, the first scene you see is of a human sacrifice, and if that weren't enough, Dracula's first appearance is just a black shadow where you can only see his eyes.
Death is once again a pain in the ass. He has three phases and takes longer to defeat than in some of the other Classicvanias. The first phase is the sickle spam only he loves to fly out of reach, while in the second he shoots a wave of five skulls at you. Fail to dodge one round, and he'll keep on going until you do (or die). The third phase has him attack you on the ground, but he's somewhat easier.
Shaft appears twice and is hard both times. The first time, he's fought after four other bosses (thankfully you get a checkpoint here) and constantly flees from you when you attack him. His attacks also do a lot of damage and are hard to avoid consistently as they trail you across the screen. The second fight pits you against his ghost, which curses you upon contact, making you slow. Worse still, he summons enemies to attack you, and there are bats spawning from above that are really hard to see on the blue background.
Stage 2 is the entrance, only it's unusually hard because it's well defended. Worse still, the zombies in the ever familiar hallway can hit you twice instead of once due to your lack of invincibility frames in this game. You also get chased by a Behemoth which does a ton of damage, and if you're trying to take the alternate path, have fun with the insane amount of mermen, bats, and peeping eyes.
Stage 4' (alternate) is pretty hard due to the frogs that are really hard to hit, a river rafting section where one hit can send you into a bottomless pit, and ever spawning skeletons if you decide to go the other way.