Btw, how does the square-cube law explain the Apatosaurus?
Presumably, it moved very, very slowly.
Likewise, it is perfectly possible to make a bipedal robot that can walk. It just will need to move very, painfully slowly, lest its joints collapse in on themselves. It would also be quite useless should it fall over, and being as slow as it would be, it would be a laughably easy target for missiles or even simple radar-guided artillery.
Barring silly science fiction nonsense (i.e. things that don't follow the periodic table of elements and current laws of chemistry), what you will have essentially have built with this "Gundam" is a very overpriced, overdesigned, and largely impractical and useless forklift. Which, if you're lucky, may have guns on it. Which, in the course of battle, will do you little good, as your time from entrance to the battlefield to killed-in-action will be less than the time it takes the writers of South Park
to kill Kenny.