Tournaments are often hosted either by players or by card shops. In addition, Konami, Upper Deck (now no longer part of Yu-Gi-Oh's Organized Play), and Shonen Jump have all organized numerous tournament systems in their respective areas. These tournaments attract hundreds of players to compete for prizes such as rare promotional cards.
There are two styles of tournament play called "Formats;" each format has its own rules and some restrictions on what cards are allowed to be used during events.
- Advanced Format
The Advanced Format is used in all sanctioned tournaments (with the exception of certain Pegasus League formats). This format follows all the normal rules of the game, but also places a complete ban on certain cards that are deemed too powerful for tournament play. These cards are on a special list called the Forbidden, or Banned List. There are also certain cards that are Limited or Semi-Limited to only being allowed 1 or 2 of those cards in a deck and side deck combined, respectively. This list is updated every three months (January 1, April 1) and is followed in all tournaments that use this format.
- Traditional Format
Traditional format is sometimes used in Pegasus League play and is never used in Official Tournaments and reflects the state of the game without banned cards. Cards that are banned in Advanced are limited to one copy per deck in this format.
Rating systems The game formerly incorporated worldwide rankings, but since Konami canceled organized play, the ratings were obsolete. Konami has developed a new rating system called "COSSY," (Konami Card Game Official Tournament Support System.)
- Sealed Format
With the introduction of the Battle Pack: Epic Dawn, Konami has announced the introduction of drafting tournaments. This continued with a second set for sealed play: Battle Pack: War Of The Giants in 2013
Casual players typically agree to follow an unofficial variant of the rules, such as multiple player duel (where three or more duelists play every-man-for-themselves) and use of the Egyptian God Cards (promotional cards from the anime/manga adaptation, which are illegal in official tournaments. These have been reprinted into legal versions, however the original promotional cards remain illegal.) For these unofficial variants of the game, the rules, such as what cards are legal or not, are agreed upon ahead of time. However, official Tag (team) Duel rules have been introduced into the main game, advertised in the form of Tag Force 2 and Championship 2008.