Rule #4: Don't flame.
Do not make hurtful comments about other members' opinions, beliefs, religion, nationality, sexual orientation, skin color, etc. This includes general hurtful or degrading comments about groups of people which other members may or may not belong to. Of course you are allowed to disagree with a person's opinions, but please do so in a respectful manner. State your disagreement by all means, but if you think the other person is the dumbest person you've ever met for thinking so and deserves to rot in Hell, just keep it to yourself. Any blatant insult will give you a nasty 30-point infraction (disabling your Debating Hall access and getting you banned if you flame again before the warning expires) which won't go away for three months.
You can also get warned for flaming if you excessively bash a Pokémon, character, movie, TV show, book, band, etc. at a level where fans of said Pokémon/character/movie/TV show/book/band/etc. can feel insulted about it too. So please no "I hate (insert Pokémon here), it's completely useless, only n00bs use it."
I might note that talking hurtfully about named people who are not at the forums is not allowed either, nor is any sort of "indirectly" giving out the person's identity such as by linking to another page with the name or allowing people who know the person's identity to give out hints in the thread. If a non-member who could technically access the forums is heavily berated in a thread, it should be completely anonymous. Do not insult members of other forums, etc. in general, either.