Water + Electric + Fairy + Flying
[Roost, Hydro Pump, Hurricane, Knock Off, Toxic, Ice Beam]
[Scald, Thunder, Charge, Ice Beam]
[Soak, Ice Beam, Scald, Laser Focus, Magic Coat, Toxic]
[Brave Birb, Roost, Iron Defense, taunt, mirror move]
[Judgement, Thunder, Light Screen, Reflect, Refresh, Recover, etc...]
[Thunder, Nasty Plot, Recover, Taunt]
The basic idea is that you have the suggested rain spam with thunder, but you also have some z-move options: Water Bubble Waterium, E-Terrain Charge Electrium, E-Terrain Soak Electrium, and Flyinium-Z Brave Birb/Mirror Move. You also have Pixialate Judgement Koko, especially for normalize shenanigans. The STAB combo is very solid super effective coverage.
The basic idea is that you have the suggested rain spam with thunder, but you also have some z-move options: Water Bubble Waterium, E-Terrain Charge Electrium, E-Terrain Soak Electrium, and Flyinium-Z Brave Birb/Mirror Move. You also have Pixialate Judgement Koko, especially for normalize shenanigans. The STAB combo is very solid super effective coverage.