Mario had an ice projectile, Pac-Man's down+B could be used repeatedly - incomplete animations of all characters' 4th custom moves in Smash 4
Did you know? That during development, Super Smash Bros. for Wii U/Nintendo 3DS game director Masahiro Sakurai and his team originally intended for every character to have four Custom Moves instead of three?
According to an anonymous Japanese Smash fan, Sakurai mentioned that to be the case in an interview somewhere, and said that the number was ultimately reduced to three as four Custom Moves per character proved to be too much to handle.
How does Sakurai know that four Custom Moves were too much to handle? That's because they'veactually tried to to implement that in the game, and were pretty far along -- in fact, incomplete animations of every character's 4th Custom Move exists on the final game disc itself.
Somebody has hacked the game and made a video documenting what these incomplete 4th Custom Moves look like.It looks like Mario's 4th Custom Moves were the furthest along -- his were the only ones that had hitboxes. Mario's 4th Custom B special might have been an icy projectile of some sort -- look at the effect when his opponent gets hit!
Other noteworthy 4th Custom Move changes we spotted include Bowser being able to move his head around and aim his B special diagonally upwards, and Pac-Man's down+B being a move that could be repeated multiple times in a single jump.
Source: http://www.eventhubs.com/news/2015/jan/05/mario-had-ice-projectile-pac-mans-downb-could-be-used-repeatedly-incomplete-animations-all-characters-4th-custom-moves-smash-4/