It'll be an intense match-up between two of history's greatest giant robots, but who will win?
Honestly I see this fight ending in Prime's favor, no contest. The Gundam has amazing capabilities for it's time, being able to shoot down whole battleships and take on even Char Aznable, but Amuro Ray, it's pilot, has little experience compared to Optimus Prime.
Optimus had been fighting the Decepticons for nearly 5 million years before the Autobots and Decepticons crash-landed on prehistoric Earth. He also displayed abilities that the original Gundam severely lacked. Episodes of the G1 Transformers cartoon showed Optimus crashing through a rock wall UNHARMED, channeling laser blasts back at his attackers, picking up an oil tanker AND THROWING IT, summoning his body parts after they'd be detached, used Megatron's transformation to shoot down Starscream WHO WAS SEVERAL MILES ABOVE EARTH at the time, and the only reason he died in the 80s Transformers movie was because Hot Rod screwed up.
Honestly, how can the Gundam compete with Optimus Prime?