While you're here, you may want to read the Rules & FAQs sticky. It's also full of fun things you should know!
The reason the FAQ exists is because little to no good, quality discussion can be derived from these topics. They're either done to death and thus no new ground to cover, or are stupi...er, simple questions that can be answered in the Single Anime Questions. Maybe even both.
Now this doesn't mean that these topics can not warrant discussion. If you REALLY think you've got a new, unique perspective, PM or VM a mod. If it's actually going to be part of an upcoming episode, or an episode that has only aired in Japan, then there's the Spoilers forum. Either way, contact a mod!
Some examples of these (but certainly not limited to) are the following:
Dub vs raw/japanese version: It's not a different show, it's not filled with blood or gore or sophisticated plots that the dub neuters. There are differences in tweaks of language (as any translation of anything will inevitably have), and the music is different for some reason or another. Still the same show.
Misty: It's been confirmed that she won't come back as a main cast member. It can't get much more official than that. If you need to talk about how million of people will flock back to the anime and stop boycotting everything Pokemon when she returns, there is a Misty club in the Club forums.
OP Edit: This also goes for endless complaining and whining on the other female leads too. Constructive discussion can be done, but it most often leads to flaming. PM a mod before opening a discussion on these roles.
Releases all his good Pokemon
COME BACK PIDGEOT (or Lapras or Butterfree)
Never catches legends
Sucks at life
UPDATE: Pikachu's fluctuating power
Pikachu's presence in general
All of these lead to no discussion and are rarely expressed in an intelligent manner. Even in threads where there is discussion about Ash as a long term character (Satoshi Haters thread), a great number of anti-Ash posts fit this spammy nonsense. This leads basically into:
Old plots never to be heard from again: Professor Ivy/Brock/What happened, GS Ball, any COTD story line
*If you honestly have NO CLUE what happened to Ivy and Brock, you need to re-watch the last episode of Orange Island Saga. It's practically spelled out for you.
*Read the interview with the artists over at Pokebeach
*Return of characters of the day (CotDs). We're not likely to hear from COTD again, especially if the region they debuted in is no longer the current region.
Shippings and Fan Fic: This hasn't been a rash problem, but it still deserves mention. There's a reason why these things have their own section, because they really aren't part of the anime. Shippings are the result of their fans reading what they want to see in the scenes they cite. Where most would only see "friendship rox!" (the theme of Pokemon), they'll see something romantic. So it'd just turn into a flame war. Fortunately, there's a shipping forum where all that talk can go.
Fan Fic isn't part of any continuity, so it gets it's own place too.
Misty/May/Dawn Debates [added by Chelc]: These go NOWHERE. Everyone has their own personal preference. Each girl is a good character, none of them are "bad" or whatever. Don't make these threads. They just end in flame wars, and I have to close the thread, and give infractions, and it's just not fun.
I HATE PIPLUP! IT SHOULD DIE! [added by Chelc]: Not only are these topics immature, but it's not like the writers even care, lol. If you hate Piplup, fine, but don't be vocal about it. Otherwise you'll be infracted for flaming/bashing a character.
Juputoru Update: This applies for any Pokemon, not just Piplup. It applies to human characters too. I've been seeing a lot of character bashing lately, and I'd like to remind you all that whining and moaning about how much you hate a given character is against the rules. You're allowed to have your likes and dislikes, but insulting certain characters every chance you get is a surefire way to get on everyone's nerves.
Character Replacements [added by Kiori]: Most people are sick and tired of the fued that is going on in the forum, including the staffs. People can't refrain from bashing/flaming others as well as characters. No more talking about replacements for main characters, thanks.
See, the cool think is these can be discussed, just not here. Many of these "banned" topics even have a place on SPPF, just don't discuss them here, please. Kthxbye.
This list will be updated and revised, especially after the FAQ is updated.
If you guys think any other topics should be mentioned, feel free to post and I'll take it into consideration, and mods are free to edit their own thoughts (though I'd prefer if they make their edits in a unique color or something like that).