Things the Players Are No Longer Allowed to Do

This is a partially funny list- but it's should give a GM things to think about when approving characters. These are all real-world examples from my games.

• Players can not attack anywhere on the earth by ricocheting blasts off the moon.
• Players can not hide in other dimensions while blasting enemies in this one.
• Players can not disintegrate Pluto or other planets.
• One player should not solo-attack any major group, even if they don't have powers. This includes the Yakuza or any national government.
• Players should not abuse time travel plots to undermine previous campaign history and paradox shut-down the campaign.
• Players should not attempt to brutally destroy Disneyland with telekinetic powers, even if it looks like they might be the bad guy.
• Players should not buy the 1 point immunity: Immunity to [insert villain's name here]'s powers.
• Players cannot put innate on teleportation.
• Players cannot make character who's "niche" is boosting all their rank 1 powers or skills with a single massive boost power.
• Player's alternate powers should legitimately stem from the primary power. Example: Teleportation is not a good alternate power of mind control.
• Players should not make characters who's goals are evil: this includes players who worship evil demons, intelligent apes who want to destroy humanity, characters who's primary motive is the death of another PC, and Yakuza Crime Bosses.
• Players should not make characters who are clones of Celebrities. This includes Jesus and Good Hitler.
• "Fuck Earth, let's go live on another dimension" is not a valid response to anything.
• "Fuck Earth, let's go live on an alternate earth where this event isn't happening" is also not a valid response to anything.
• When a power is banned, that ban extends to other powers which have the exact same effect, even if the framing is different. If postcognition is banned, using communicate:objects to emulate postcognition is also banned.
• "This is not my problem" is not an appropriate response for Super Heroes.
• "This is above my pay grade" is not an appropriate response for Super Heroes. (Rorschach stood up to Dr. Manhattan after all- even if he DID lose).
• Postcognition is not as accurate as actual time travel- no pause, rewind, etc.
• Players cannot use "precious metals" as the only item that blocks X-ray vision, and then spend their time collecting precious metals.
• Players cannot buy off their weaknesses immediately after they become relevant.
• Player's cannot open teleportation portals on the autobahn so that cars crash into the villain. Teleportation portals to the sun also create bad effects for the planet.
• Players cannot open teleportation portals that are restricted to only specific items to get around the previous rule- for example, a teleportation portal to the sun, selective to only enemies and not solar radiation and heat to protect this end of the portal.
• Players cannot spend down time using inventor/ritualist/etc to amass a stockpile of every power to use whenever.
• Players can no longer kill John Travolta when he's doing nothing to the party.
• Players can no longer attack the pope just because he's around.
• Players can not come to a special session with one other player just to arrange that player's death.
• Players cannot stretch all believability and change character's personality so that the character can learn something the player is already aware of and act on things he shouldn't know.
• Players cannot ricochet a blast off the moon to hit someone on the other side of the world.  

Just a bit, but as you GM you see those power gamers trying to go all "mechanics first" on you. Thought a humorous post on some of the goofy things that players have done in the past would prepare a new GM on what to expect.