I just simply used my flaffy's thunderwave to hold down its speed down and stop its rollout attack and used thundershock though flaffy and bellsprout went down I was able to use Flash to lower milktank's accuracy and make rollout less of a threat then finished the battle with noctowl who was level 22 Female using peck and tackle. But I don't really see why it was so hard to beat even though I only won because I used strategy XD. But really what was it that got on your nerves cause it wasn't hard really unless you walked in the gym as soon as you arrived in goldenrod city with underleveled pokemon.
I beat her on my first try for anyone who wants to know. And yes people I do know it had Milkdrink so quit saying that.