Mechagodzilla

With its Fake Godzilla disguise rapidly becoming more and more compromised by Godzilla's attacks, the Black Hole Planet 3 Aliens decide that the time for subterfuge is over. With the flick of a few switches, Mechagodzilla's full appearance is revealed, set to some cool camera angles accompanied by particularly bombastic jazz composed by Masaru Sato. In the ensuing battle, Godzilla's thrashed by the machine and comes out the loser, though Mechagodzilla itself sustains enough damage to force the aliens to recall it for the time being.

Example of:
Robotic Reveal