X Bomb

The X Bomb (called a Cross Bomb in Japan) is an item from the Kid Icarus title, Kid Icarus: Uprising. It appears as an explosive item in Super Smash Bros. for Nintendo 3DS / Wii U. Upon detonation, the bomb explodes in two lines of flames that span across the stage in either an X-shaped or cross-shaped formation. Bowser Jr.'s Final Smash in which he turns into Shadow Mario and paints an X over the screen to harm other players is nearly identical to this item's function.

X Bomb
File:XBombExplosion.jpg
First appearance	Kid Icarus: Uprising (2012, Kid Icarus) Super Smash Bros. for Nintendo 3DS (2014, Mario-related media)

Masahiro Sakurai stated on Nintendo's Miiverse network that the X Bomb is from Kid Icarus: Uprising and is not to be confused with an item of the same name from Meteos. Though the design for the X Bomb in the game is definitely based off Kid Icarus: Uprising, it actually behaves more like its Meteos equivalent. It's further confusing to note that the Japanese name for the X Bomb, Cross Bomb, is actually the name of an item in Meteos, and the name is completely irrelevant to Kid Icarus.