Extrem X:
At the Character Select Highlite X and Press & Hold DOWN and hit the Space Bar. 
X will teleport onto the Intro stage in a purple shade on his legs and arms 
(More Pruple towards the top of his legs and arms). After completing the Intro 
stage go to Web Spider's stage and get your Leg Enhancments. Instead of JUST 
the Leg Enhancement you get EVERYTHING only 4X stronger and a diffrent color. 
You also get Unlimited Use of the Powerful "Nova Strike". 

Dark Zero:
Nothing Special about him but it's A LOT more fun going through the Game with 
Zero in his Spy Armor. At the Char Select screen Press and hold UP and hit the 
space bar. Zero will Teleport onto the Intro stage wearing his Black Spy Armor.