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

Which G1? RX1782 can stalemate the cartoon or Marvel G1 Optimus. IDW would tear the original Gundam a new one. Mixing feats from other convoys from the Japanese continuty makes it a big mismatch in Optimus Prime's favor.

The OP specifies the composite linked. Do you believe it's a mismatch in light of Gundam speed and reaction time? I'm also curious what about his IDW incarnation you believe is superior to his cartoon or Marvel portrayals since most of his feats I'm aware of come from the cartoon, like lifting an oil tanker or planetary reentry?

I've seen all of the original MSG. Amuro has super human speed but his RX178 still gets hit by regular humans in giant robots on a regular basis. In the cartoon, his main adversary is Megatron but he fights a whole mess of villians stronger than Megatron in the comics including Scorponok, Sixshot, Thunderwing, and Jhiaxus. As for Marvel, I believe Optimus was nerfed at around issue 80 when he lost the ability to transform. To my knowledge, he hasn't regained his Powermaster body.

I should also add that Optimus has been in a war for millions of years while the original Gundam was only deeply involved in the One Year war. Prime faced all sorts of unbeatable foes (ie Unicron, Thunderwing, Underbase Starscream). Amuro has struggled with more experinced foes including Char in suits like the Zaku, someone Amuro could've beaten handily at the end of the series.

Optimus wina

Screwattack did a great video on this

https://drive.google.com/file/d/1VRQ6-sr0nFukiMDGFH-Uek9G-S1xtej-/view

G1 prime wins but not so easily, IDW comic Prime stomps.