To become almost invincble, you must have all of the energy tanks, all the bodies, legs, and helmets, and weapons. Now equip the "Ultimate Foot" foot chip which contains every foot effect, the "Absorb" body chip which wil insure you do not flinch when hit, the "Auto-Charge" head chip so that you wont have to take the time to charge your weapon, and "No Element" chip so you wont have any potential weakness in your attack. Also make the Z-Saber your main weapon and Recoil Rod as your sub weapon so you can reach high heights and attack enemies at a semi-ranged distance. Make sure you've made all Cyber Elves that can improve Zero's stats grown-up and used, because that'll make you that much better. Always keep your sub tanks full incase an emergency healing is needed. I hope this hint helps!