According to Bulbapedia, there are 4 Pokemon with the ability Wonder Skin.
Sigilyph's Slot 1 ability is Wonder Skin, so you do not need Dream World access for this.
However, with Venomoth, Skitty, and Delcatty, for whom Wonder Skin is a hidden ability, this is more difficult.
In Pokemon Black 2/White 2, there are only a few sources of Pokemon with hidden abilities that do not involve connectivity to the 3DS (Dream Radar), or the Nintendo servers (Wi-Fi/Global Link Event, Dream World).
For future reference, in case another Dream World ability catches your eye, you can obtain these Pokemon through:
Venonat can be found in the Hidden Grotto on Route 3 (Pond). Evolving Venonat will give you a Venomoth with Wonder Skin.
However, neither Skitty nor Delcatty can be found in Hidden Grottoes, nor do the in-game events contain their Dream World variants (Such events include the recurring Braviary on Route 4, and Musharna in the Dreamyard). N's Pokemon can only be caught if you performed a memory link with a previous game (difficult to do without using the physical White 2), but it appears that N did not have Skitty nor Delcatty.
The last legal/legitimate option in this case would be to breed a fresh Skitty. However, since the Pokemon cannot be obtained any other ways, this is a bit of a Catch 22. But if you would like some peace of mind about using "Genetically Modified Pokemon", you can utilize save editing software to give yourself a temporary female Dream World variant to breed, and then release it afterwards, keeping the eggs. Because most Dream World Pokemon arrive in the Entralink at Lv 10, hatching a Pokemon at a low level would probably feel more legitimate.
Save restoration through the link given above by Theodore is also a good idea. I would suggest that perhaps you enable Memory Link on your physical copy after dumping your save file onto it, to allow for N's Pokemon to be caught when you play on your emulator again.
Finally, a full list of Dream World variants and their in-game locations can be found here.
Best Answer
If you are going to want the DSEMU core I would suggest using it itself. Unless you can find a video saying that It is for OpenEmu because certain setup steps would be required.