IGA personally retconned Sonia Belmont from the series. Castlevania Legends is the only game to be completely retconned from continuity as IGA returned Circle of the Moon and both N64 games back into series canon (as side games to the main series). I like the idea of a female Belmont, but truthfully, Legends made no sense since Sonia and Alucard have a child together, meaning every successive Belmont would not only be Dracula's descendant but also completely unable to touch Vampire Killer. Yeah, fail.
This game should have a good variety of characters. Off the top of my head, there's Soma Cruz, Joachim Armster, Walter Berhard, Maxim Kischine, Stella and Loretta, Isaac, Saint Germaine, and Death.