Come on, man. Of course Alucard appears stronger in SotN than in Dracula's Curse. It's called console limitations/console improvements. And you can't say "Well, this character was level 99 in game X" because there are no "levels" in the games' universes. Alucard may be able to win in an arm wrestling contest, due to his vampiric powers, but never in combat with a Belmont.
I don't really understand the armwrestling thing, but..I think one must reflect upon the characters powers within the boundries of game series universe itself and each character's potential strenght developed. And if you would maximise the powers of both Richter and Alucard in sotn and put them in a fight, I don't see any other outcome than Alucard winning..as everyone knows, he was exteremely overpowered in the game, even more than Richter.
And none of us can judge any further than what we witnessed in sotn, since they haven't showed up anymore since then as fighting characters. sotn was the last representation of them, and so their powers are simply those presented in sotn.
Also, the Belmonts are humans who battled and defeated both Dracula and Alucard while in their late teens/early twenties. Even with Dracula's and Alucard's hundreds of years of experience they still could not defeat the Belmonts.
Clearly Alucard's strenght increased drastically since he left his father..it's also mentioned in the recollection CD.
but you know, that is just for the present, nobody knows what Konami will bring up in the future..