I personally enjoy Castlevania: Judgement in a mostly ironic way, but part of me always wonders what would have made it something that I could enjoy less ironically. As it stands, it's horribly balanced and the gameplay is way too centralized around building up your super meter and using it faster than your opponent. Additionally, the camera always picks the worst angles and most of the character designs are awful(Especially Simon).
If I were going to fix this game, I'd focus mostly on fixing the balance of the game with a few other touches. First of all the camera needs to be fixed; it should always try to have one character on the left of the screen and the other on the right instead of going into weird over-the-shoulder angles if one player walks towards the screen.
The rest of my proposed changes have been condensed into spoilers to make this post easier to read.
Subweapons
Breaking candlesticks/torches/pillars should only drop hearts. This is to eliminate the randomness that comes from breaking an object; there's no reason for players who are low on hearts to sometimes get screwed over with random weapon drops, plus the stopwatch is overpowered and shouldn't be in the game.
Supers
Right now, most supers drain about 40-50% of the opponent's life bar, which is what makes the game centralize so much around them. While giving some characters supers which deal that ridiculous amount of damage makes sense(Like with Aeon and Golem), most characters, especially ones whose supers have stupid hitboxes like Trevor's, need their damage reduced to 15-20% of a health bar. While this change will inherently make matches last longer and as a result favor zoning characters like Death by allowing them to more safely run down the timer, I think it would still make matches more engaging than just whittling your opponent's health to below half and then pressing X.
Dracula
Dracula, to put it simply, needs to be given more options. He has some good moves, but he also has a lot of bad moves, and some of those could be replaced with moves that better compliment him. He's built to be a slow projectile-based character, but his projectiles aren't commanding enough to give him any significant presence. To remedy this, he needs to either gain a powerful, long-reaching projectile to threaten approaching foes, a fast, mid-range attack to keep people off of him, or for the charge time on his charged special to simply be sped up to allow him to more effectively cover himself with it. If his moveset were to go unchanged, his mobility is still so bad that he can't just play keepaway after landing one stray hit, which would be the only way for him to win without new attacks. Additionally, his lack of mobility prevents him from farming hearts as effectively as every other character in the game, and his jump drains his meter, which is completely unnecessary. Dracula's mobility needs to be buffed by either making him walk/teleport faster or letting him float without draining meter. Seriously, there isn't a single character who can't still hit him while he's in the air.
Alucard
Alucard seriously needs to be touched. He's basically this game's Meta Knight - his moves are fast, safe, and very rewarding to land, not to mention the absurd speed and hitbox on his super. As for exactly how to fix him, he needs to have one of these attributes taken away, and given that his range comes naturally with a sword, I'd say his damage should be shafted. Fast, long-ranged strikes are very fitting for Alucard, and changing his moves to do less damage is a good compromise that keeps the feel of the character mostly the same while also making him less threatening. Also his projectile needs about twice as much endlag as it has now because he can basically just hold A and mash B to win.
Aeon
As for Aeon, he's in need of fewer nerfs than Alucard. While he does score easy wins against the majority of the cast, he doesn't feel unfair to play as or against. While Alucard felt blatantly overpowered, Aeon just feels very, very good. However, to keep him in line with the rest of the characters, some changes need to be made to some of his more ridiculous options. His laser should last about half as long but do 1.5x as much damage. This is mostly just because being caught in that thing is the worst feeling in the world, but also fits as a balance change to make him feel the same but be more fair. With both of these changes to his laser, it will hurt 75% as much as it used to while only locking you in hitstun for half as long. As for his other specials, they're fine. His best option, time freeze > super, is fairly balanced because of the limited range on time freeze and because it's the only way he can reliably get his super off. However, as Aeon is one of the few characters I feel should keep the 40% damage on his super, his access to this option needs to be limited. To accomplish this, the charge time on his specials should be increased. I think he should charge at a rate that makes it so that he can only use time freeze in the last 20 seconds of a match, and he shouldn't be able to use it during the match if he used either of his other specials. I think he should only have enough time for 3 lasers, 1 laser and 1 extension, or 1 time freeze in a single match. Making his resources this limited will encourage him to not spam the laser as it will usually bar him off from his super for the rest of the match, while also indirectly buffing the laser and extension by giving Aeon the element of surprise when using them- if the opponent knows Aeon can only use his super if he holds onto his charges for the whole match, they won't expect him to use his laser and are more likely to get hit by it.
On a side note; anyone feel like delving into this game's files and finding out if it can be modded to the same extent as Brawl? I looked around and found quite a lot of useful files in the data but couldn't find/make sense of anything that could hold things like attack data or character animations(aside from Shanoa and Aeon's super animations, which are stored in the same file as their models and can be viewed with BrawlBox).