The Item Switch is a menu in the Super Smash Bros. series where players can select what items they want or do not want to appear in matches, as well as the overall frequency of their spawning. Players cannot, however, alter how common items are compared to others (for example, Heart Containers will always be one of the rarer items).
In Super Smash Bros., players must unlock the Item Switch by playing 100 Versus Mode matches. The player can then select which items they want to appear in a match and how often they appear, from very low to very high. Green Shells and Red Shells cannot be switched individually; they are both covered under the item "Shell".
In Super Smash Bros. Melee, the Item Switch is available by default. Like in Super Smash Bros., players can select which items they do or do not want to appear in a match and how often they appear, from very low to very high. However, they cannot turn off the container items such as Capsules, Barrels, and Crates. Instead, they must set the item frequency to none for these items to not appear.
The Item Switch returns once again in Super Smash Bros. Brawl. This time, it has an on/off switch for instantly turning all items off or on, and they can turn off container items without having to set the item frequency to none. However, players can no longer put items on very low or very high. Instead, they can only put them on None, Low, Medium, or High. Also, collectible items such as stickers cannot be disabled without setting the item frequency to None.