I feel like doing any sort of challenging run in Gen 7 is impossible because the games are made to be really easy and friendly. Even if you start limiting yourself on things it just becomes really easy. I've given up on 2 nuzlockes and a wonderlocke after 3-4 gyms because I just didn't care for how easy it was.. Now if we're talking about a challenge, I ask anyone to try playing a game with Shuckle.. I did a solo once on Emerald using one and while it has good defensive stats, in Emerald you get about one decent move and that's rollout, so you spend most of the game using X-accuracys and X-Attacks then spamming rollout on your opponents.
Got to say that while I've done over 50+ Solo's in Emerald, I've got to agree with Jd that monotypes are great, I'd probably rank them higher than solos purely because of how difficult or easy one can be. Depending on the game and the type, some are incredibly easy and a breeze while other types and other games can be a real pain to go through, this contrasting of difficulty makes you feel a lot more accomplished than having an overleveled mon beating everything in 1-2 hits.
I advise anyone wanting to do some fun and unique challenges to consider Type-Lockes and EliminationLockes. Type locks are probably easier for newer people and add a real nice twist to a nuzlocke.
