Bros. Ball

Bros. Ball is a move learned by Mario and Luigi in Mario & Luigi: Partners in Time. In this move they both turn into a ball and can now move faster. Additionally, the Bros. Ball lets Mario and Luigi go under walls in the game. Later on, Mario and Luigi learn the ability to flatten Baby Mario and Baby Luigi. This move is called Baby Cakes.

The Bros. Ball ability was also used much earlier in the game by the L33t Hamm3r Broz. The two Hammer Bros. had an attack where one would use their mighty Hammer to smash another into a sphere before hitting him at the Baby Mario Bros.; this attack is very much like Bros. Ball. Also, one of the L33t Hamm3r Broz.' Hammers may break during an attempt to do this attack, resulting in a bouncy version of the Bros. Ball not used by Baby Mario and Baby Luigi.

This move may be a nod to Mario Pinball Land. Also, the "Rolling Combo" seen in Sonic the Hedgehog 4: Episode II bears a striking resemblance to the Bros. Ball, but it is functionally different.