As far as minimizing damage goes, on the current ultimate event maps where Pest damage seems to be quite high, the most effective ability that I've seen (only from helper squads, I don't have any of these girls myself) is the enemy attack reduction - Bride Oncidium and Cherry in particular.
The usefulness of skill boost is why I'm still dithering over plunking down some money for Apple, even though I have Lycoris and several other magic golds (Setaria, Evening Primrose, German Iris, Moonvine and Tachibana) and I don't find Apple's art all that appealing.