>>281226507
Physically speaking, Garp would make it to Namek at least. The steel cannon ball he was chucking like a mile away was bigger than the mountain Goku had to put all his strength into lifting pre-Super Saiyan, which was made of stone and not steel. Then we learned Goku was using Kaioken like the entire time for a 10 to 20 times boost before he finally got Super Saiyan for the 50 times boost. Not only that but Goku ended up using Ki to destroy the mountain where as prime Garp was cracking mountains with his fists as training.

So if we assume primary Garp was way stronger than the one already one handed throwing mountainous steel cannon balls and Super Saiyain would actually only be about a 5 times multiplier from Kaiokenx10, and Garp was duking it out already with guys equal in strength to him so he has the durability to match, Prime Garp could probably duke it out with Namek Super Saiyain Goku if we don't count ki blasts and talk strictly fighting.

So given Prime Garp was equal to Roger in a fight, Roger would likely make it on Namek as well in a physical fight.

Of course given people can just blow up planets and it's not just a melee fight, that changes things a bit. So I'd say if they fought on Supreme Kai's planet which was way stronger and could withstand Kid Buu's attacks, they'd probably have a good chance at making it to at least Super Saiyan level fighters.