A modern, but still silly, version of that, with Jackie Chan as an agent of the UN's "Godzilla Force" who's assigned to protect the Twin Faeries of Mothra's Island. Picture him carrying their little wooden travel-box, and having chop-socky Kung Fu fights where he has to protect the box and keep it upright.
The red-rubber-suited aliens not only have Mecha Godzilla, but they've planted a brain-control device on Godzilla himself, and have a guy aboard their saucer driving him with a "Waldo"-type controls, and they've got both 'Zillas rampaging through Japan.
So Agent Jackie ends up infiltrating the saucer, fighting and beating the guy in the Waldo control and takes over Godzilla. Jackie controls Godzilla in a new fight against Mecha Godzilla, which is either shot with Jackie Chan actually wearing the Godzilla suit, or done with CGI and Motion Capture with Jackie performing while wearing bulky enough padding to to restrict his movements to Godzilla levels.
With Jackie's skills and Godzilla's power, Mecha Godzilla is destroyed and the aliens are routed.
I'd watch that!