-The Dragon Ball Z law:
Whenever you attack, you must yell as loud as you can.

-The Kaiba Law
If it is an anime in which the people are doing something like a children's card game or if the rules of the anime are actually EXPLAINED, the villans and sometimes the heroes can screw these rules anytime they want, because they have money/green hair/power/whatever. This also includes using moves and combos in a card game that are unable to be performed in a real duel of said game.

-The Naruto law:
EVIL ninjas are the ones who wear black and attack from the shadows. GOOD ninjas are the ones wearing brightly-coloured-clothing and will only attack when they are provoked.

-The Shikamaru Law:
Using the exact same trick in different or creative ways will win EVERY fight.

-The episode-stretching law
A temporary cease-fire is called whenever a flashback or speech has to happen.

-The Dick Tracy Law
you can tell villains are evil if they have hideously-deformed faces. (Commonly seen in Ruroni Kenshin)

-The Sesshomaru law
Villains that AREN'T hideously-deformed/horribly scared are bishounens who are popular amongst fangirls.

-The Tea Gardner law
During a flashback, it is possible to remember something that happened if you were thrown accross the field or while you were knocked unconscious.

-The Zabuza law
If you one-up your enemy or your enemy one-ups you, then they MUST explain why so you or your enemy will learn to expect it. And if they learn what they just did, they will explain how they can counter it.

-The names of the attacks law
You must yell out the names of all your attacks so the viewers will know what attack you're using and when to use it in Fanfics.

-The law of men's clothing
Pants are indestructible, while shirts will be discarded of or destroyed very early.

-The Hiei's dark-dragon-whatever-law
Shadow flames must ALWAYS be purple and black.

-The Naraku Law
90% of the fights with the main villians themselves are just to taunt the heroes, so thus the villain will escape at the very last second, giving more excuses to extend the series' run.

-The Kagura law
And sometimes the villain's sidekick/number one henchman will escape 100% of the time becuase s/he has an important plot role in the future. ;p

-The Digidestined law
There must be at least one set of filler characters who may or may not be important to the story by having a relationship to the hero or the villain. During fights, these people will sit back and make comments about the fight. Sometimes they will be the ones doing the explaining about what the attacks do or their fighting style, because obviously the villains don't have another ally who may be listening in.

-The Kuwabara exception:
The secondary characters may sometimes have powers and capabilities of their own, and will sometimes even fight, but all the important fights are to be fought by the hero only. During these fights, they will either sit back and comment or be unable to fight for whatever reason. Whether they're too exhausted to use their powers from a previous fight or were knocked unconscious/killed, they rarely help the hero out even though they'll be clearly outmatched until they go Super Saiyen, because the villain can slaughter them easily. ;p

-The Kamiya Kaoru law
Oftentimes, the secondary characters are important to the story and have a reason to be there because they are obviously the love-interest of the hero. ;p

-The law of weapons
Anything can be used as a weapon, even puppets.