Your UU team looks alright.
If Uxie is using U-turn, then its nature should be Impish, so that U-turn's power isn't weakened (yes, I know U-turn coming from uninvested neutral 75 Attack doesn't hurt much but still...)
Slowking's Fire Blast is weakened in the rain. Instead, either use Ice Beam for hitting Grass and Dragon Pokemon, Psyshock/Psychic for a secondary STAB or Dragon Tail for phazing.
Like Slowking, Nidoqueen's Fire move is weakened in the rain, so it can use Focus Blast as an alternate way to deal with Steels, despite thevredundant coverage with Earth Power and low accuracy.