If you're not gonna use copyrighted characters, you guys should look into getting more artists' OCs. Unless you have some banger character-designs in mind, I don't think your own original characters are gonna cut it, especially if they're as bland as Angel's. A big draw for the first game was the recognition-factor.
Despite there already being lots of porn fan art of her, they probably should still get permission 1st. Maybe a different route the devs could take is how Shady Lewd Kart gets permission from other NSW game creators to use their OCs. That way, PS2 will still have that crossover factor but free of copyright from Corps that don't like nsfw of their IPs
