I saw the posts about incredible Snorlaxes, and I thought I'd post a similar story.
I decided to try playing a Nuzlocke run on my X game after beating it once, since I didn't find the game to be especially challenging. It was fun, don't get me wrong, but I figured that this might be the perfect game to try as a Nuzlocke, since I'd always been too scared of failure in the past. I lost plenty of Pokemon on the way, along with some beloved team members, but by the time I got to the Pokemon League, I felt like I had a pretty solid team (though I had unexpectedly lost my Tentacruel to Victory Road, so no Water type).
I went in with Delphox, Pidgeot, Snorlax, Tyrantrum, Magneton, and Xerneas (completely untrained; he was a last-minute replacement for Tentacruel and I didn't expect to use him). I defeat Malva without too much trouble. Drasna is the same, though there were some troubling close shaves. I'm feeling alright, so I battle Wikstrom next - and he kills Delphox and Tyrantrum. Then Siebold wipes out Pidgeot, Magneton, and Xerneas with his Dragon Dance Gyarados. Snorlax managed to beat him once Waterfall ran out of PP, but I didn't like my prospects of facing Diantha down with nothing but a Snorlax.
Still, I had to try. And, incredibly, Snorlax seemed to be born to fight Diantha. Yawn put dangerous foes to sleep, Return was incredibly powerful STAB, Crunch took care of Gourgeist, and Brick Break smashed right through Aurorus's Reflect. I could hardly believe it, but I guess I should've expected it. That Snorlax carried the team through the most dangerous battles ever since I caught him.
tl;dr: Go Snorlax!