i just went with an fenekin(14) aron(10) marrel(7) and an pikachu(6)i beat her with one pokemon remaining didn't even use one item in battlebut i did use 5 atk vitamins on aron and 5 sp atk vitamins on fennikinit was fairly balanced
ah yes, items that boost pokemon's stats, a thing to expect to before in the 1st gym, not near the middle or end game, silly me for not expecting that.