Vanessa really had it all. She has a big, fat rump (the best type), her butt cheeks are individually animated and her ass jiggles quite a bit. And that jiggle isn't generated by a physics engine like almost all other ass jiggle in videogames - it's manually animated by Kenichi Ueda. P.N.03 is most probably a "prequel" to The Mercenaries game in Resident Evil 4 & 5. It shares the same combo system and it's all about shooting enemies within a contained area. The Mercenaries is better, though. Ueda went on to be the creative director for Resident Evil 5.
You can clearly see how it jiggles. But also note how the upper part of her thighs jiggle with her booty, and how her cheeks jiggle differently. This is manual animation, which means it always jiggle exactly like this during this animation.
The famous wiggle should not be confused with the jiggle. Wiggling is when she shakes her ass, jiggling is when her ass shakes.
For some reason the mp4 videos won't play properly here. Just click on the image and you should be able to see the video on imgur.
This is the wiggle you get with automatic upgraded to just one slot instead of two. As you can see, both her ass and thighs jiggles with the motion.
This is when she does a backspin. Her ass jiggles quite a lot here, so you can easily tell it's not firm. But that's a good thing, I think!
This is her normal running animation, but captured via the Dolphin emulator to get the camera that close. Her cheeks bounce up and down a lot with every step.
I don't think there's any other videogame character who shows her ass in a thong, has this much butt jiggle and who also shakes her ass so much. Vanessa has a better butt than 2B, because 2B lacks jiggle.
And I mean, just look at her rump:
Look at the hip to waist ratio. Look at the ass to thighs ratio. You could play around with her cheeks for a long time, she has such a great ass it's a shame the game is forgotten.