This is the original Optimus Prime from Transformers G1 against the Gundam RX-78-2 piloted by Amuro Ray.
Optimus Prime has access to the abilities of his incarnations listed here (except for Alternity)- http://www.screwattack.com/news/death-analysis-g1-optimus-prime-0
Amuro Ray as an adult and experience from all official appearances, RX-78-2 has access to all weaponry regardless of the RX's carry capacity.
Scenario 1: On Earth
Scenario 2: In space
Scenario 3: Both fields open
CIS off, winner by death or BFR