I mean, even in the game MC with 0 skill (so 0 training too) gets killed by a couple of gun thugs at the restaurant if he tries to fight. He literally doesn’t know how to use his powers. Then he monstrifies from the damage and later gets burned alive by Malik, but whatever, just to complete the point.
Oscar, while still in his human body, managed to fatally wound, or maybe even kill, the red-eyed monster. Then he dies and transforms from damage, but it is what it is. If you would give him Michael-level prep on the fight and a lot of guns, I certainly bet on him.
Your own example doesn’t really work, I don’t know how else to say it. Sure, MC with 74 powers probably could have a very good chance against superhuman Oscar (who has only 12 Power and 4 Skills), but his strategy literally was "Look at the dude and punch the dude". And even then I doubt that MC without any transformation (again, 0 skill = 0 training) could easily kill him. His red light was just fine in stopping MC when he was running away with Danica even though MC might have been stronger stat-wise at that point. His light is Hax.
But yeah, sure, I don’t really see how Oscar would’ve killed the MC, considering his regeneration is instinctive and doesn’t require training. So I guess you could count that as a win for the MC. At least against superhuman Oscar.