I think a match against both is even, maybe a little harder against a skilled Nightwolf ..... Johnny is the best rushdown character in the game, he is a machine approching and coming to fight, but, Mileena as well if she decides to leave behind the counter-attack nature, and go toe-to-toe, if both decide to rushdown the entire match and Johnny does unforgiven mistakes, he can
be put himself in a very vulnerable position, missing lots of
flip kicks, so, it's a very even match, 3 points.
Nightwolf has more tools, and can act as a zoner against Mileena, so, depends the level of skill the players behind him put in the match. Nightwolf, in my opinion, is , overall , the most complete character in the game, having weapons to deal with a lot of different situations. Could be 3 , and
sometimes 4.