Ohtani (8-5) emerged with a win despite serving up a career-high four homers, going 6 1/3 innings while allowing five runs on six hits. He struck out nine and walked one. At the plate, Ohtani walked three times and scored two runs.
Mike Moustakas, Trey Cabbage, Zach Neto and Tyler Ward homered for Los Angeles, which earned its fourth win in a row.
Henry Davis hit two home runs and Ji Man Choi and Jack Suwinski also went deep for Pittsburgh, which fell for the 13th time in 16 games.
In the top of the fourth, the Pirates kicked off the scoring with back-to-back solo homers from Choi and Davis. Ohtani, who had struck out five of the first 12 batters he faced, left pitches high for both blasts
Ward then walked before Moustakas socked a three-run homer, giving the Angels a 4-2 lead
Two outs later, Cabbage added to Los Angeles' lead with a 448-foot bomb to center field for his first career home run, capping the five-run frame. The 26-year-old rookie was playing in his sixth major league game.
Oviedo (3-11) was down after four innings, having yielded five runs on three hits and three walks with four strikeouts. His streak of winless starts reached 11, during which he is 0-8 with a 4.83 ERA.
Ohtani opened the top of the fifth by hitting Nick Gonzales with the first pitch. Suwinski made him pay for the mistake by taking Ohtani deep. Suwinski notched his team-leading 20th home run of the year and got the Pirates back within 5-4
Jose Hernandez came in relief of Oviedo in the bottom of the fifth and allowed two home runs in the first four batters he faced. Neto led off with a shot to left-center, and Ward contributed a two-run homer with Ohtani on first to push the Angels' lead to 8-4
Davis added his second home run of the night off Ohtani in the sixth.
Angels closer Carlos Estevez tossed a scoreless ninth inning to pick up his 22nd save of the season
--Field Level Media