In Mega Man X3, you will find yourself finally
using Zero's coveted sword. The author speeds
through the game very rapidly, and uses the sword
to beat the 8 bosses very quickly the second time around.
Though this run is done very quickly indeed, there are
some minor stylistic improvements that could be made
such as boss optimization, higher accuracy, and unnecessary
damage being avoided.
The page "Mega Man X Tricks" explains some of the tricks
that are and/or can be used in the X series games.