Idk about shin being so weak compared to the base saiyans. He was able to survive being beaten up and showed some resistance to Fat Buu. I dont see him doing that if hes lower than the saiyan base form.ought to oneshot considering the large amount of evidence for Base Saiyans >> Shin would mean Shin would be lucky to be on #18's level via scaling and it doesn't seem as though he can use his paralysis for combat purposes like Zamasu.
SS2 Bardock VS Enraged Gohan (vs. 2nd form Freeza)
Are you counting the whole Ginyu Force and Freeza fight as the Namek arc? If so, Vegeta started off strong but ends it shivering at 2nd Form Freeza, intentionally getting himself injured by Kuririn in a frantic attack, delusionally calling himself a Super Saiyan and crying as he gets stomped and killed. Bardock was way more badass.He would most likely lose to Super Baby Vegeta.
Namek arc Vegeta VS OG Bardock in terms of badassery