This has been established multiple times, because it's such a sweet combo that everyone would want to try it. The answer is no: Wonder Guard cannot be Skill Swapped, nor can it be Role Played. It can be Traced, but there's no way to use Trace to get a Dark/Ghost-type with Wonder Guard. The best you can do is get a Porygon2 immune to everything but Fighting...and maybe give the Porygon2 Conversion and an Electric-type attack so that it can switch to being immune to everything but Ground...