let's see if i can crack this.
So, we know that Dracula gets stronger with every resurrection, but not exactly how much. I'll try and figure that out as time goes on.
At the very bottom of the scaling chain we have Slogra and Gaibo. These two individually were able to give Simon a good fight just prior to his battle with Death and Dracula immediately after. They also serve as an enemy for Trevor and Hector in Curse of Darkness. Technically I could place the Lament of Innocence cast here
Just above them, we have Death (Curse of Darkness), as Slogra and Gaibon are considered his direct subordinates and he's obviously significantly stronger than them Death AFAIK is equal to the Time Reaper which is partially where Low 2-C comes from.. Just above Death, we have Dracula (Curse of Darkness), and by extension Trevor and Hector as they both defeat him within the 3-year span of Dracula's Curse and Curse of Darkness. This applies to Sypha and Grant as they're comparable to Trevor.
Something something Christopher and Soleil go here but i don't think they're canon. If they are, just add another ">" on there as that era is pretty featless.
Fast-forward a few years, and we have Simo, Death (Castlevania IV), and Dracula (Castlevania IV). I don't think these should be that much stronger than the Curse of Darkness incarnation as they lack the feats, but Simon should be at least somewhat stronger as he defeated Dracula on his own, wherease Trevor had help from Grant, Sypha, and Alucard.
Next up we have Juste Belmont. I'm not sure how he fits into the scaling as he doesn't directly fight Dracula, just a wierd gross flesh monster version of him, but he is mentioned to be extra powerful due to also having Belnades blood in him. I should mention that he should be at least 2x baseline as there are actually two copies of Castlevania in this game. This would make even a heavily weakened botched resurrection version of Dracula (Harmony of Dissonance) 2x baseline, which is a good marker going forward. Eat your heart out, Ganon.
After that we have Richter Belmont, Death (Rondo of Blood), and Dracula (Rondo of Blood). This shouldn't need much explanation. He's stated to be the most powerful belmont at the time, Alucard describes his power as supreme among vampire hutners, he's the first Belmont that can use the Grand Cross technique, et cetera. Speaking of which, this leads us to...
Alucard (Symphony of the Night) is by far the strongest character we've seen so far. Even after sleeping for centuries, a heavily weakened version of him without any of his equipment (Which he also doesn't use in Castlevania 3, mind you) was able to beat Slogra and Gaibon working together. Later on, he can even one-shot and fodderize several of them as they reappear in the mines. Of course, he also defeated Richter and Shaft, the latter of whom was able to summon/maintain two copies of the castle, as well as Dracula.
I'm iffy on placing Shanoa this high, as she only defeated her game's incarnation of Dracula (Order of Ecclesia) by using Dominus, but she did have to weaken him first so it could work, and can survive channeling Dominus through her body, so it's probably fine.
Once again, I'm iffy on 'John Morris being this high, as using the Vampire Killer ends up... yknow, killing him. But Jonathan Morris and Charlotte Alui should certainly scale. Despite not having Belmont Blood, Jonathan unlocked the Vampire Killer's full power and there's some stuff in Portrait of Ruin about him relying on his own strength rather than that of the Whip. He and Charlotte were also able to defeat 'Dracula (Portrait of Ruin) and Death (Portrait of Ruin) After they had fused together.
Now we're getting to the Good stuff. Julius Belmont is stated flat-out to be the strongest Belmont who ever lived. Alongside Alucard (1999), he was able to actually destroy Dracula once and for all. Even against Soma, he was holding back. Which, once again, brings us to:
Soma Cruz (Aria of Sorrow). The cream of the crop. How strong is he? Well, he defeated not only Death (Aria of Sorrow) mid-game, but also Chaos, the source of all of the powers of darkness across the entire series, to whom Death and Dracula are mere facets of its being, yadda yadda. Really strong stuff. Soma Cruz (Dawn of Sorrow) is even stronger than that. And finally, we have Dark Lord Soma, the absolute strongest character in the series whom Julius Belmont (Dawn of Sorrow), Yoko Belnades, and Alucard (Dawn of Sorrow) had to work together to defeat.
I think that covers everything. The full chain is then something like this:
Slogra + Gaibon (CoD) <<< Death (CoD) <<< Dracula (CoD) < Trevor = Sypha = Grant < Slogra + Gaibon (Castlevania) <<< Death (Castlevania) <<< Dracula (Castlevania) < Simon (Castlevania) << Death (Harmony of Dissonance) < Juste < Death (Rondo of Blood) <<< Dracula (Rondo of Blood) < Richter Belmont < Maria's Magic (Rondo of Blood) =< Maria (SotN) =< Richter (SotN) <<< Dracula/Galamoth (SotN) < Alucard (SotN) <? Shanoa < Death + Dracula (Portrait of Ruin) < Jonathan + Charlotte (Portrait of Ruin) <<< Julius (1999) = Alucard (1999) <<<<<<< Chaos < Soma Cruz (Aria of Sorrow) < Soma Cruz (Dawn of Sorrow) = Julius (Dawn of Sorrow) = Yoko (Dawn of Sorrow) = Alucard (Dawn of Sorrow) <<< Dark Lord Soma
