adding to what Azeria had said, it can be worth it to change the field effect by concealing it temporarily with a terrain move if need be or if you can setup a chance, with an attack changing the field itself naturally as half the E4's strength is how dominant their types are on their chosen field and expect it will take a number of retries. But yeah simply put, take advantage of whatever the field will offer or figuratively...or literally burn it to the ground and figure out when you have a chance to setup as it's invaluable as an opportunity if you find an E4's mon can't threaten you much, in which case ya might enjoy using battle items (X items) if ya dont have setup buffs like swords dance