Pomeranz worked the first four innings, scattering three hits and three walks while striking out seven.
Ottavino (3-1) then took over, earning the victory with three more scoreless frames during which he allowed only one hit.
Carlos Gonzalez and Jordan Pacheco drove in runs as the Rockies snapped a three-game skid.
The Dodgers' Chris Capuano (10-8) was saddled with the loss despite yielding only two runs on nine hits over seven frames, striking out six.
With the loss, the Los Angeles blew a chance to wrest first place in the National League West from the San Francisco Giants, who fell to St. Louis earlier Monday.