McGuinness isn't defeating 616 Cap.
The suit isn't all that powerful. He is nowhere near, say, Spider-Man in raw power. The suit provides him some resistance to electricity and such but we still see him being effected by blunt force trauma. His durability isn't that much better, if at all, than Cap's.
I say 616 Cap takes him down due to being a far better fighter, alot smarter, and a much better tactician. Hell, he probably even has the advantage when it comes to reflexes. The batsuit is of a mesh material if I'm not mistaken so pressure points are a viable option for Cap.
None of McGuinness' gadgets will prove effective as nothing he has will be breaking through the shield. Then he will attempt to take Cap in close-quarters combat where he will then proceed to get wrecked.