I tried to translate some regulations for Cosplayers at Tokyo International Anime Fair 2013 which has updated recently. It may be interesting to compare to other Cosplay events in other countries. Although it does not apply to all of Cosplay events in Japan, It is a good indication to understand big Cosplay events in Japan. Most interesting points I find is that you cannot enter the venue with Cosplaying. It means that you should change your costume at the Cosplay changing room in the venue not allowed you to wear the costume from your home!
Original Version in Japanese: http://www.tokyoanime.jp/ja/visitor/cosplay/

Available time for Cosplay
Cosplay Area 10:00-16:00
Changing Area 10:00-17:00 (last admission till 16:00)
Cloak 10:00-16:00
* You may need to wait when the changing room is crowded.
* The cloak room is only available for Cosplayers.
Since the cloak area is available for all cosplayers,
we do not bear any responsibility to the individual luggage.
Please pay attention to your belongings on your own.
Notice for Cosplay
Not only people who love cosplay but also who come for other objectives on the event. Please be considerate of those people.
All Cosplayers must go through the front desk before you cosplay.
To enjoy Cosplay at Tokyo International Anime fair, you need to register. (500 JPY)
You cannot use the chanign room and cloak without the registration card.
We prohibit cosplayers from coming the the venue with cosplaying.
e.g. wearing wig, costume and cosplay make
Limitation for Costume
We prohibit Cosplayers from wearing a costume for some occupations who have a special authority. e.g. Police, fireman and self-defence official.
Please take into cosideration your costume especially when you wear an armor which may hurt others. When you move in the venue, please remove the parts to avoid hurting others.
Also please remove a helmet, eyepatch and mask which interrupts your sight, when you walk.
* You need to a person to help you if you wear the special costume which may interrupt your sight. The person you help has to register as a cosplyer.
* We may ask you an area you can walk and move if we consider your costume is too dangerous.
We prohibit you from wearing an overexposure costume or a costume makes other people unfomfortable. If you wear a plunging costume, please follow the front desk staff.
About an exposure of your costume
Tokyo International Anime Fair prohibit the overexposure.
Please don’t show your skin by painting yourself or wearing body tights.
Please don’t show your skin directly. When you wear a mini skirt and costume has a deep slit, you need to wear a stockings, tights or spats.
We prohibit Cosplyers from showing your underwear. Our staff will check your costume if it is suitable for the event.
About an limitation for cosplay, properties and fake weapons.
Please take care of those costumes because a lot of general attendees come to the event.
There is no limitation of the size of the weapon, but please pay attention to your weapon when you walk and move at the venue.
Only big weapon which can dissolve are admitted.
* The defintion of the big weapon is over hight 1.3m * width 60cm.
You may have a limitation depending on your size of the weapon.
Please don’t bring the weapon outiside of Cosplay area.
* There will be a place where you can leave your weapon.
Prohibited items
Real sword and guns and other edge tools.
Model gun and Air gun which can shoot.
Burnable dangerous objects or drastic medicine.
Ridable things (e.g. Bicycle and roller blade)
noisy stuff (e.g. whistle and radio casette)
Things which may make the venue/people dirty (e.g. paint and stage blood)
Other things the staff consider it’s dangerous
Others
Here is the notes within the Cosplay room/floor.
– You cannot change your costume or make up without the changing room.
– Please share the area and room. You cannot share a large area on your own.
– You cannot use the stage blood and hair spray at the venue.
– Please don’t play the weapons and take photos which men and women embrace/hold.
You can smoke only smoking area.
Please don’t leave your belongings at the venue.
We cannot be responsible for lost or stolen items.
Shooting Cosplayers
Only Cosplay floor is the area you can take Cosplay photos.
When you take a group photo, we may ask you a time constrain to avoid a heavy congestion.
Before you take photo, you should have permission to Cosplayers.
If not, it will be considered a spy photo. It applies to when you take a photo by your mobile.
When we find any voyeuristic behavior, groper and spy photo, we will call the police.
We allow you to take a photo and prohibit you from shooting video.
Please note that it is my roughly translation not official version. If you have any questions or concerns, please ask them directly.