Since Smash had the opportunity three times to add a Castlevania character and didn't deliver, I think Superbot & Sony have the right now to add one of them.
i 100% agree. i personally just feel gabriel would be the perfect choice because of all his weapons and powers.
symphony of night (one of the biggest games of castlevania ever)
castlevania lament of innocence (i believe this one is also really big)
castlevania curse of darkness
castlevania the dracula x chronicles
castevania lords of shadow
i may be missing some, but those were some big ones for playstaation of the series, not all of the castlevania games ever were playstation, but a big chunk were.