Back to the topic of the mech costumes,
here is a couple of examples of what they'll resemble (with a few exceptions)
This guy's madcat costume
In my opinion he made this far too large, and should have used thinner PVC for the frame. The missle racks also didn't need to be nearly that large, and for the purposes of keeping things simple I'd plan on putting nerf launch tubes in the arms and dual paint guns in the nose, leaving the missle boxes just be decoration.
His chicken legs work but he made them too long and a bit too fat.
Kid's madcat costume
This kids costume looks good standing still but he didn't really do the joints too well, hence it only wobbles around.