I recently (several weeks ago) learned of something called The Nuzlocke Challenge. As you can see at the link, there are just 2 rules: Only attempt to catch the first pokémon in an area, and any feinted pokémon is dead.
I am going to attempt this challenge with my heretofore unopened Soul Silver edition of Pokémon. I'll make a few tweaks, though:
1. Instead of releasing a feinted pokémon, I'll have a PC box labelled "RIP", which will act as a cemetery. Let me never forget my fallen friends.
2. I'll try to catch legendaries for the challenge, but I'll never use them. That works both ways: Even if a legend is the 1st pokémon that I encounter on a route (likely via judicious use of Repel), it just "doesn't count" for me.
3. This is more of a clarification, but it's assumed that gift pokémon don't count against any area limit, especially as some are no-choice gifts, anyway.
4. Another clarification: I'll assume that each PokéWalker route is an area unto itself, and thus that only the 1st poké radar encounter counts.
5. Though it's not actually in the rules, I'm taking a tentative pass on breeding, more in keeping with the spirit of the challenge than the letter.
Though I started Heart Gold with Cyndaquil, I'll also be starting Soul Silver with Cyndaquil, owing the the comparative rarity of fire-type pokémon. I'll post here with occasional updates.