Breather Level: On the Alucard path, opting to finish Stage 5 rather than going to the Sunken Ruins takes you to the Catacombs beneath the castle. It's unusually short, has fairly simple challenges, and both Grant and Alucard have ways to make it even shorter. Even the boss (Frankie, who also appears in Stage 5 of Sypha's route) is pretty easy.
The Castle Entrance is this on all paths, despite the fact that from this point on you die in four hits. It's short, light on the bottomless pits and tricky jumps, and allows opportunities to get lots of hearts. The boss is certainly not that easy though, considering it's Death.
Ensemble Darkhorse: Alucard was a relatively minor character in this game, but he evidently had enough of a fanbase to later become the main character of Symphony of the Night.
Game Breaker: Once you unlock Sypha, there's little reason to switch back. She may not have any special jumping or controls like Grant or Alucard, but her spells are very powerful. Fire's easily the least helpful as it just shoots in a straight line, but it's still a strong attack. Ice will freeze enemies into blocks that can be killed with a single attack there after and can be made into a platform if you're quick, it also freezes water hazards which can be helpful against the currents. Lightning fires in all directions and will homing in on any enemy, including Death and Dracula, which will track them even as they're teleporting or dashing across the screen. Her staff may have shorter range than Trever's whip, but its animation is quicker and can be rapidly spammed.
Death is this as usual. He flies around summoning scythes and you die in four hits like the encounter in the first game, only he has a second form this time round. Fortunately, the second form is easier than the first form, and the first, while really hard, is not as brutal as in the first game due to you having more options and room to manouver.
Stage 7-5. The only way to advance was to wait for the falling blocks to form a platform for you to ascend. If you got hit by a falling block, you were likely dead, and had to repeat the process from the start.
Stage 7 as a whole could count, seeing as it's about as long as 2 normal stages. The best part? The hardest parts are AFTER the falling blocks, so every time you game over, you have to go through them again.
There's also Stage 9, which is almost all the different challenging segments remixed into one big ass stage. The fact that you die in four hits at this point is the icing on the cake.