Once again, we have the generals telepathic communications. Anyhoo, since it seems like I wasnt as obvious as Id hoped, Id better clear up exactly who they are.
Green = Kraid (referred to by the blue voice)
Blue = Magus (Kraid implied him as being a sorcerror)
Red = Ridley (reffered to by the grey voice)
Grey = The Mother Brain (The voice is giving all the orders.)
Sorry for any confusion.
Mangus? Huh... Really didnt expect him, really.