Item storage

The Item Storage is a gameplay feature which first appears in Super Mario World. It allows the player to keep an additional item in reserve for use within a course. The Item Storage has reappeared mostly in handheld games (like New Super Mario Bros.), although Super Mario 3D World is an exception.

Super Mario World
In Super Mario World, it is named Item Reserve Box. If Super Mario gathers a Cape Feather, for example, he will turn into Caped Mario and his former power-up, the Super Mushroom, will move into the Item Storage. After taking damage, Caped Mario will turn into Small Mario, and the reserve item will drop down automatically. The item will pass through the ground and platforms, however, and will fall off the screen if the player does not collect it fast enough. The player may also make the reserve item drop down whenever they want by pressing. The reserve item, once grabbed, will not bring any extra Points (unless it's the Cape Feather, which will still give 1000 points if Mario is Fire Mario when he grabs it, though only in the SNES version). Super Mushrooms will always replace the reserve item when collected in Super, Cape, or Fire form, regardless of the Item Storage's contents.

New Super Mario Bros.
The Item Storage was reintroduced in New Super Mario Bros., working like it did in Super Mario World. For example, if the player is Super Mario and the player has a Fire Flower in the Item Storage, they can tap the item with the and it will automatically appear on the top screen. Unlike in Super Mario World, if Mario, while powered-up and holding a higher-tiered power-up in the Item Stock (like the Blue Shell), grabs a Super Mushroom, or earns one from a Toad House, it simply gives 1000 points to the player, instead of replacing the reserve item. Reserved items will also act as if they were knocked out of blocks normally when released, rather than passing through and off the screen. The Item Storage also will not drop its contents unless the player uses it. The Power-Up and Mega Mushroom Toad Houses also give power-ups that go straight to the Item Storage.

Super Mario 3D Land
The Item Storage later appears in Super Mario 3D Land, acting in the same manner as in New Super Mario Bros. However, due to the game being a 3D Mario game, the reserve item pops out of Mario or Luigi and falls in front of him. Additionally, P-Wings are instantly stored upon collection and are replaced by most other power-ups; the game will ask to confirm the player's intent to use one if tapped.

New Super Mario Bros. 2
The Item Storage reappears in New Super Mario Bros. 2, where it behaved exactly as it did in New Super Mario Bros.. Collecting all of the Red Coins in a Rainbow Course will give an instantly-stored Gold Flower.

Super Mario 3D World / Super Mario 3D World + Bowser's Fury
The Item Storage appears once more in Super Mario 3D World, acting the same as it did in Super Mario 3D Land. The icon appears on the near bottom-left corner of both the TV and the GamePad screens; it is used by pressing or tapping it on the GamePad screen. Depending on the number of players present in gameplay, the Item Storage can hold up to four different items. In the Nintendo Switch version, Super Mario 3D World + Bowser's Fury, is used instead. That version is also the first game where storing an Invincibility Leaf is possible, as the Mega Mushroom and Invincibility Bell supersede it; it reverts to a Super Leaf upon clearing a course or dying.

The Bowser's Fury mode of Super Mario 3D World + Bowser's Fury lets Mario carry up to five Super Mushrooms, Fire Flowers, Super Leaves, Boomerang Flowers, Super Bells, and Lucky Bells each; pressing opens the inventory menu to choose a power-up. Bowser Jr. gives the power-ups to Mario in this mode.