Which one is "non-Nintendo"? StrategyWiki? they're cool .
That's actually a valid reason enough to me lol. Yes they are only part Nintendo, but they are kinda amazing. They are well-established and have invaluable editors (*cough* Moydow). Pretty much, we don't want to say "Not Nintendo? Get outta here." Pretty much, they were good enough to make us look beyond the fact that they're not completely a Nintendo wiki. Plus, not many wikis actually focus on the strategy/walkthrough parts, so SW helps make up for that.
As for fanon, well it's that fanon. It's much looser and kinda fun. I don't see a reason why not. Pikmin Fanon also was kinda attached to Pikipedia, it would have been really rude of us to turn them down.