Im stuck. ON the fourth sigma level, after Berkana, you have to fight Sigma. After you beat the first form, you have to fight the big robot thing. How do you inflict damage onto it? No matter what I shoot at him, he doesnt lose any damage!!!

To cause damage to this form of Sigma you must first lower his armor. You do this by landing hits to his head. He will eventually become exposed (you can tell because he looks like his first form).

well my friend just showed me this game and it was the first megaman game ive played it was cool but i cant beat the 2nd form of sigma and i went through all the levels with x i didnt know i could change to zero and now he has no health or weapons can i still win??

Well sigma is easy for me I beat him on my first try ( both forms) well to beat him first you should make sure x has the arm part,leg part,and body don't get the head you won't be able to use more than 2 upgrade parts.

you will beat the ordinary sigma by own instict....
beat the robot yellow and blue form(Ulitimate buster of x will show him)-----x'll need a dash up move!!!------ for the red(z-saber)

hit sigma's chest!!and all is over for him!!!!