Cotton would likely be the preferred media, as it has more "bite" than a foam applicator pad or MF. However, some plastic is very scratch sensitive, so I would say try it on a tiny bit first. You would be better off having a little scratched area to fix than the whole gauge cluster. If it's sensitive, then use MF.
Chrome (real chrome, not the chrome looking plastic) is pretty stout, so it won't be scratched by PP.