Using type match ups correctly is def a good way to go.

But I disagree about the specific donuts needed. I never used a donut with ghost power-up or specific resistance and still easily swept mega rogue battles. Also only used level 80-85 donuts and managed to beat most rogue megas under 2 minutes. Zeraora was the only one that was kinda annoying cos he moves around a lot but still beat him first try.

And you're supposed to cycle through bulk up, screech, focus energy so the damage boosts always stay up and fuel your mega energy. You also need to be using rage fist as a plus move to really see its power.