Destroy all the mavrics [exsept Sigma] with Zero still alive. Go to the second stage of Sigma's lab. After the waterpit go into the next room as Zero. Fight the bug. It will fall on Zero and X will come running. Zero will tell you he can't take any more. And tell you to take his sabor.
Final Battle with Sigma
To battle sigma, start the game and go to the password section. Then enter 3217-8153-6772-3823. You will see zero's face if entered correctly. Now you can battle sigma with all upgrades and the Z-Saber.
Final Battle with Sigma
At the password screen enter:3217-8153-6772-3823. Now you can face sigma and have everything including zero's saber.
Final Battle with Sigma
At the password menu enter the follwing numbers: 3217-8153-6772-3823. You will now face the final boss(sigma), have all weapons, all upgrades, all robot suits, heart containers, a super chip for your arm, full energy containers and zero's saber.
