Just wanting to know the details behind it.

I would say the flash. If he was trying from the very start. The flash can be beaten by batman if he has the right things though. For example the flash is kinda weak to ice but most likely the flash is winning

Batman is a great tactician so if he’s given enough of time he could surely come up with a strategy to beat flash
He’s done that in comics and in animated series

Nice response, I agree!

The flash maybe fast but Bruce Wayne can stop a lot of threats if he has time to prepare for it.

Flash can be the fastest man on earth but Bruce is the best tactician and a skilled fighter he can come up with an idea and could defeat flash