'Locke Doc

So, you want to Nuzlocke, huh?
Whether this is your first run through or you've done this countless times before, I hope this has something you can use.
Let's start with the bare bones rules of a Nuzlocke
first pokemon you see on a route or in a town, that's the pokemon you catch. No exceptions, if you fail to catch it, tough shit. Move on without it.
If a pokemon faints, release it. Or box it if that's something you'd prefer.
Nickname each pokemon you catch.

That's the basic Nuzlocke, and it's hard enough as it is, but if you're a bad enough dude to add some new rules, here you go.
-No Pokemon Centers-
-No Pokemarts-
-Limit your leveling to X levels per route-
-Mystery egg Nuzlocke You get six eggs from Wfg, hatch those, and those are the only pokemon you can use, same Nuzlocke rules apply.-
-No using repels-
-Set your battles to set style, which makes it so when you make an enemy pokemon faint, you are not present with the "Keep battling" or "Switch" option. it takes up a turn instead-
-No dupes clause. EX: You catch a psyduck, then the next route a Psyduck shows up, you don't catch the second duck. You go by the next encounter, and catch that.-
-Team Rocket Nuzlocke-

I'm sure there are tons of others, I'll add to this list as recommended.

Check Dude's list for a Power ranking on the difficultly of Nuzlockes.

Other types of runs (Non Nuzlocke)
Team Rocket Run, Only stealing pokemon from other trainers
-Monocolor run-
-Monotype run-
-Mystery egg run-
-Ash Ketchum Run. Only use pokemon Ash has acquired, no evolving pokemon he had unevolved.
NU Run. Use only pokemon from the NU tier on Smogon. This can be applied to all tiers.-
-Survival run. No Pokemon Centers, no marts, only six pokemon allowed. however, when a pokemon faints it doesn't die like in a nuzlocke, if you have a revive you can use it. You choose what six pokemon to capture, and you can release a pokemon if you want replace them. Pickup is a godsend here.-