weather could help with many battles but not like this. Castform goes completely on the weather, literally, he can change it and use it to his advantage. rain dance, hail, and sunny day. Depending on which you dont want - change it to thunder wave. weather ball uses the weather's type to attack, rain dance/water, hail/Ice, sunny day/fire. leftovers to make you last although you can put damp rock or others that lengthen the certain weather you chose. draw back with hail, constantly damages your other pokes.