Thunderbolt over Psychic leaves Meloetta without STAB, which is bad... Maybe over U-turn though, since Meloetta gets forced out a lot by faster Pokemon. Not sure if it's worth the trade-off, but I'll have to try it.
Also, I was playing a bit more earlier and got pretty much wrecked by a Claydol/Cobalion/Ferro core in Rain, although I almost managed to win with DDMence (fuck confusion), bringing it from 1-5 to 0-2 O.o