The Flash gets training from Rational Man with A Shotgun. Who can he beat now that he couldn't before?

The Flash gets training from Rational Man with a Shotgun, who explains things like how not to job really hard for the sake of it.

Rational Man with A Shotgun also explains to the flash, that he could carry a pouch of iron balls, and throw them far faster then he could normally run, creating plasma spheres and what have you, and that this could be further enhanced by using an Nth-Metal sling to truly accelerate whatever is the best material for such a device.

I.E. A 10gram sphere of Nth Metal accelerated via the Flash using a sling, could probably go right through the Earth or similar.

Rational Man teaches obvious things like, if the Flash jobs so hard Gorilla Grodd grabs him around the neck, just place hand on Gorilla Grod's arm, vibrate hand at super speed, and watch Gorilla Grod's arms shatter.

Who can The Flash beat now that he couldn't before, or is it a moot point considering the power level of the Flash anyway?

R1: CW Flash.

R2: DC comics Flash. Wally West.

R3: DC comics Flash. Barry Allen.