Can I just re-list what I agree with, but with slight tweaks? XD
-Make Dracula Vlad Tepes, but still having a connection with the Belmonts (I really have no problem with him being Mathias, but I'd choose for him to be Vlad Tepes for it to coincide more with Bram Stoker).
-Make Vlad Tepes REALLY be more active into Lament of Innocence. Like, really more active as in "Vlad and Leon storm Water's castle together, but it ends up to be a trap set by Vlad himself". Have Vlad be playable.
-Reintroduce Sonia as the first human to face Dracula, but make her die, prompting Trevor to return to Wallachia and go after Dracula himself using the Vampire Killer.
Lament of Innocence: Lose the whole Dracula/Mathias connection entirely. Have Mathias instead be like Walter; A stepping stone to help strengthen the early Belmont family. To prepare them for when they must face the real Dracula.
Remake a new Legends game with Sonia reinstated. Have a backstory describing Vlad's rise and fall, his betrayal to Mathias (now King Mathias of Hungary), and stealing of the Crimson stone. Vlad loses his wife due to the Turks deceit and this act prompts Vlad to become Dracula. The Japanese backstory of legends would be used rather then the US version. Sonia is Trevor's mother and she trains her son to be the next hero of legend.
One of these two scenarios really needed to be in the actual story. They are much better than what happens in-series.
*Bring Dracula more in line with Stoker's novel.
Agree entirely with this.
*No Tepes. It's a title, not a surname.
But I like 'Alucard.' It's claaassiiic.
*Incorporate more traditional vampire remedies/killing methods.
*Do away with the 100 year resurrection gimmick.
At the very least they need to come up with a better reason for why he keeps coming back.
*Explore the origins of other vampires and monsters, i.e., Carmilla, Mummies, Medusa, etc.
*Fix the name translations to their intentional references. Fernandez instead of Belnades, Ricardo instead of Lecarde, Orlock instead of Olrox.
*Incorporate loyal gypsy slaves of Dracula as villains for the Belmonts to confront.
This is a good idea, and could help craft good characters.
alucard grant & sypha would play a role in curse of darkness
I agree with Grant and Sypha but not with Alucard. That doesn't seem... correct.
more insight into the Belmont family, as well as dracula & lisa's relationship
The games could really use deeper characterization.
or, if it did happen, incorporate more "military-esque" vibe in the story. brauner would be replaced by hitler,
Not Hitler himself, please. Hitler has been done to death and back in every medium ever. I certainly don't, however, object to making more references to WW2. PoR really failed in that respect.
-Have Simon's revelation about the curse not be brought to him by a "mysterious woman ghost". Make him either notice this alone, introduce a new character or a ghost from a previous character.
Perhaps he notices something is wrong with him and goes to the Belnades clan for help or something.
-Richter fails against Dracula imediatelly, not after 6 years, prompting Alucard to come imediatelly. Have SotN be about Richter AND Alucard fighting inside the Castle, but having Alucard face Dracula at the end.
This is an interesting thought but leaves a few things unclear. What happens to Maria, for example; does she exist as a PC in this instance or is her relevance scrapped? Or is her character re-worked entirely?
-Introduce Drolta Tzuentes clearly on Bloodlines. Have her be the second-to-last boss.
-Have Circle of the Moon reintroduced. The Baldwin are a branch of the Belmonts, and their job is to keep Carmilla at bay using a Vampire Killer replica (The Hunter Whip), parallel to the Belmonts against Dracula. Sometimes, both could overlap. Nathan Graves could be the ancestor of the modern Morrises.
-Do something else with Futurevania (Aria of Sorrow on). There's a cult right? Make them an actual threat. And an actual cult with some scary fucked up people. Have the world shit out some other groups of demons now that Dracula's out of the picture. I dunno.
Agreed. The cult in DoS was a disgrace. Every time one of them was on screen I cringed at the awfulness.
I'd retcon things around so that the adventure mentioned in Circle of the Moon's backstory was actually Order of Ecclesia. Shanoa would have been Nathan's mother, and both Morris and Nathan's father would be among the villagers with ties to the Belmonts.
A good idea. Shanoa could stand to be a little more relevant. Thematically it makes sense. Shanoa having to sacrifice herself to use Dominus, the Morris clan having to sacrifice themselves to use the whip.
The period before Trevor in which the Belmonts had been banished
Maybe some new Belmont that had gone to North America
More of a story around the vampire killer being given to the Morris', as well as the Belmonts reclaiming the whip.
The Demon Castle War
All of these should be expanded upon. I don't think there's a single Castlevania fan that isn't sour about not getting the 1999 game.
The whole idea of why the Belmonts cannot touch the whip would be dropped entirely if it cannot be explained in any coherent or rational way.
Yeah, that plot point was lame.
*The stock of the whip is the Vampire Killer, not the entire whip.
Better still, the whip reshapes itself an accordance with who is wielding it.
I would have Joachim play a larger role in LOI, maybe as a anti hero you control through parts of the game's story leading up to him taking on Leon and losing and thus passing his power on to the whip or something. Or more likely a unlockable story prequel mode for him that has a actual story and features his exploits to overthrow Walter.
I would make a remake of 2.5D remake CV3 and add the Devil Forgemater element into it as a new addition.
I agree with both of these. I liked Hector and Isaac and I think they would be great characters in the series provided that they were executed a bit better.
LoI, as much as I like it, is a total ham-fest that ends with you having more questions than answers. The Ebony and Crimson stones need to be re-worked or at least better explained, as does what exactly Death is. I thought that the way the Vampire Killer was created was interesting but it needed to be executed a bit better. Joachim and Mathias need to be re-worked. Joachim's run should function story-wise like a prequel, or he should have more relevance in the main story. Mathias either needs to be re-written as the King of Hungary who Vlad wrests the stones from, or he needs to outright switch places with Vlad for some reason and have it not be totally contrived.
No romance between Alucard and Sonia. This doesn't fit with Alucard's belief that his bloodline is cursed and should disappear from the world as is indicated in SotN, and that would be a belief he would have held very deeply around Sonia's time.
CV3 has some bosses that are kind of 'meh' in that they are re-used. I'd replace these with other figures from the series, maybe leave a reference to Isaac or Magnus in there.
Curse of Darkness needs to be a bit nicer to Trevor and Co. As much as I like St. Germain, he doesn't really contribute anything to the story; improve that or scrap him. Work Sypha and Grant into the story instead. Hector could inquire about Alucard. Death and Isaac working together should have put Trevor out of commission. Before and after fighting Dracula, Hector should make parallels between what happened to Rosaly and what happened to Lisa.
The Adventure games don't have bad stories but they, like the Simon games, could use more meat to them.
I actually like HoD's story... but it's aesthetics could use a little work. Can we start by re-designing Juste, poor fellow? He looks out of place amongst the Belmonts. Give him red hair like his grandfather or brown hair like his descendant at the very least. The overall palette should be more subdued. As far as actual story goes, Death needs to not appear so much to taunt Juste like a derp and the script in general needs some series re-working.
I like the idea that Richter failed from the get-go and immediately becomes the lord of a false castle, and this surge of dark energy disturbs Alucard. My only problem is that I can't figure out any way to work Maria into the story without it being... weirdly contrived, unless her character is changed completely (for example, if she is Richter and Annette's child and Alucard meets with them before even entering the castle). Or, if Maria is an adult from the get-go, that would work. If there's some 'romance' included and one assumes that the Lecarde clan are the result of it, then the Lecardes are adopted. Period. Alucard doesn't want biological children brought into this world.
I'd make CotM canon, but either CotM or HoD needs some story tweaks to make them less... samey. Overall I think HoD has the stronger plot so I would tweak CotM more, tying it in with OoE and making this the beginning of the Morris clan.
CV64 games could also be made canon but like the other games, they could use some plot tweaks.
Portrait of Ruin needs to be much, much darker in every respect, especially considering that this is the game that takes place around WW2. One of the two PCs needs to be bolstered emotionally by the other even though they're both cracking under the horror that is Castlevania. This gives the partner dynamic more strength from a story perspective. Graphics and character designs need serious tweaking to be in line with the story changes. Nazis, maybe. Not Hitler himself though. So sick of Hitler in video games.
1999. Make it exist. FFS, Konami.

Aria of Sorrow was decent, but I would change some things. Hammer should be working with Yoko, and be a Danasty descendant even if the surname is lost. Yoko should meet with Soma more than once to make it more upsetting when she is taken out of commission. Graham should be a little less obviously evil until he is seen stabbing Yoko, and Arikado should be made more ambiguous to the point where Yoko doesn't know who he is and can't vouch for his character. Also, change Arikado's name. It's stupid. Julius needs to be handled better as well; it's weird that he was just wandering around as an exorcist between 1999 and AoS. Did Alucard know he was alive? Meh...
Dawn of Sorrow. Make the cult not be completely pathetic. Have there be other cultists in the game aside from the key members, or explain where all the other cultists went (all the dead in the final boss room, perhaps?). Cut a lot of the light-hearted banter between characters, make them more focused/down to business or have them talk more about darker aspects, to make the game less derpy. Again, change the art style, and have one of the endings reveal who it was Alucard had looking after Mina. Do NOT confirm which ending is 'canon.' Make Hammer playable in the bad ending.
In general: in the sorrow games, it's not clear who Alucard is working with, save that he belongs to some sort of organization which make be a government organization and that he trusted one of his associates with Mina's safety. Hmm... In Curse of Darkness, Hector and Julia are implied to have set up a refuge for people like Hector; people of darkness who reject evil and have nowhere to go. Between Symphony of the Night and 1999, I would have Alucard find this organization, and he works with them to find the prophesy and then protect the Belmont line until 1999. This shadow organization would by this point be international and is, imo, a far more interesting group with story potential compared to the 'time travelers who aren't allowed to do anything' group. It also shows that things are not so terrible for defectors like Hector/Alucard as they were in the 1400's, as society has gotten a little less stake-happy over the centuries.
There are some other things but they've slipped my mind for the moment. I'll throw them in if I remember them.