K' (by Dampir, of course) and Benimaru could be the perfect models for D.D and Rook respectively-
Sorry to disagree, but they don't have similar movesets. In the case of D.D and K' their clothes are way too different, starting with the sleeves. Their body build is also different, being D.D a bit hulkier. In the case of Rook and Benimaru, could work, but putting the Remy wig...just no. Rook's hair is spiky while Remy is straight.
Also, Avel/Death is VERY different to Rugal. If you say Adelheid...could work, since they're both slender, but those baggy trousers of him would be a problem.
I don't know if the project is going to have a story behind, so in this case, I'd say going with the easiest(yet dumber) option: they've been abducted to another dimension, so Ingrid is searching for them/whatever. So you can center the efforts in the other fighters better.
Keep the good work!