oh! I forgot! weather effects don't (fully) work in the Arena [halved effects, no hail damage, 50% SS damage)
and not at all in the Nether (irrelevant)
and if you want, you can randomly call in rain during the day, or even a thunderstorm
during thunderstorms, it counts as night time, and pokes can be randomly struck by lightning. so warn us at the end of the round if it will storm (it's part of minecraft's coding and whatnot, so you can include it if you want)