X-Factor is a technique that can be used by all fighters, excluding Master Hand and Ganon-Bot. It is heavily influenced, if not directly taken idea of Ultimate Marvel Vs Capcom.
Usage and InfoEdit
It is activated by pressing all four buttons A, B, X and Y on the 3DS and all directional buttons + B on the Wii at the same time.
X-Factor can only be activated once per match, but has many uses, such as increase damage and push force on attacks and turning the tables when you are losing a match.
X-Factor is strength depends on how many times you have been knocked out.