...part of what makes challenges challenging is working with what's available to you and making it work.
To an extent, I would say yes, but as a general factor, I'd have to disagree. What makes challenges actually challenging is the fact that we
follow a set of rules; working with what's available and making it work is only what comes next - and that is where the "fun factor" is decided by an individual.
Being forced to use very limited pokemon is not everyone's cup of tea, that's why I think many challenge makers simply allow hacking -- even if the challenge is completely possible without. Convenience. If anything, these are completely optional.
There are people who have fun by simply following strict and limited rules, but there are those (more or less,
"casuals") who just want to go through a given theme while having a lot of freedom. I tend to tilt on both sides from time to time.
It's hard to put up some challenges, especially the difficult kinds. It's like telling people that this bitter-looking drink can be ingested, but the only way to make some even dare try the thing is to pair it with salt, cheese, or milk.
I have probably misled you when I mentioned that "it might be required to hack." For that, I do admit that it would have been unnecessary. I wasn't thinking clearly. My issue for the hacking part was more on the freedom of choice, looking at all the options in general, than actually making the challenge simply work as it is :/