OK!!! Lets see Grendizer is more powerful that any robot like Mainger Z or even Great Manzinger
The reason is because Grendizer was made from a metal that is more strong than any metal that Mazinger Z or Great Mazinger has or any other robot
Also, Grendizer is from outspace and not from earth and the people who built Grendizer is made not from a different metal but also was built by great technology that the people on the earth dont know about this technology.
That what i believe GRENDIZER IS THE BEST AND STRONG ROBOT ^__________^