Offering these services for a certain amount of money in exchange is basically the same as selling copies of any DVDs or CDs with warez content downloaded from the internet (piracy) that are forbidden by law. So, if you get caught, it's likely that you will be in trouble and face serious accusations from Nintendo and other game companies because you don't own the rights to what your are selling. Even if you do it for free. It's a bit different if you do it for yourself, but if you are caught you still are doing no good from the law's perspective.
So, in the end, I would say that advertising it is pretty much the same as attaching your name to these illegal practices.
As long as you are fully aware that you are taking some risks here, it's entirely up to you doing it or not.