The way these raids work, you'll almost never get a perfect IV Walking Wake. So here is one. Perfectly legal, so you can trade this, and use it in competitive. All the other factors (EV/Friendship) are set to 0 so you can modify them on your own (do not change things unnecessarily, and know what you are doing).
WARNING: Like all the Pokemon you haven't caught in your own game, there is a very little chance that you can get yourself banned. So keep that in mind that projectpokemon.org and I will not be held responsible for it. Use at your own risk.