I just thought of another potentially problematic continuum.

Touhou. I can see the PPC having problems with it for several reasons.

1) Unless I'm very much mistaken, very few cast members have fully established personalities. How could we discern what's OOC?

2) Almost every single character has a story-breaker power. This includes, but is not limited to, Flandre Scarlet (who can destroy anything in her line of sight), Sakuya Izayoi (who controls time and space), Reimu Hakurei (whose power of floating extends to floating away from reality), Yuyuko Saigyouji (who can make anything die), and Yukari Yakumo (who can do whatever the hell she feels like). How would you discern a Sue in the midst of all this? An online acquaintance of mine made a Parody Sue (called Marisu, of course), but I don't know how we'd find the genuine article.

3) At least one character would be immune to neuralyzation. Because there are so many loosely-defined powers that encourage creativity on the part of their users, there's bound to be one who can evade memory wiping. For a specific example, Yukari would probably achieve it through something cheesy like manipulating the boundary between vulnerability and immunity, or remembrance and forgetting. (spot the reference!)

Nobody in the PPC has tackled Gensokyo before, and I think I can see why.

I would argue that something like something like 8-Bit Theater has established itself as a spin-off continuum standing on its own. I wouldn't say AU, because as far as I know the webcomic characters are not like the original game characters.

Red vs. Blue is an example of something similar. It's set in the Halo universe, but never really interacts with it directly and has established its own canonical storyline.

IMO, 8-bit Theatre would be an AU. Fanfic would work, I suppose, but the entire thing is an alternate storyline using the same characters (plus a few from the other games) in a more self-referential way. Considering the webcomic has merchandise and a following of its own, I'd say AU bordering on different continuum. It's fanfic almost in a similar way to, say, Nuzlocke comics.

I'm not an expert, though - just my take on it!

You've made two posts in a row, and maybe that would have been better asked on the same thread you asked about Five Nights at Freddy's? There's some really neat stuff going on right now (like filk! and plotholes!) so not pushing them down unnecessarily with a double-post would probably be better.

Especially when your previous post had people explaining this to you. It makes it seem like you're just using the Board as a FAQ. :(