Hi! I have a couple of suggestions that I hope can help.
This is a PokePaste of the Team with my edits.
First, I think that this team would work well with rain because of thunder, and also electric terrain because of, well, the electric types.
I don’t know why Magnezone is choice scarf because of its bad speed, but sturdy makes it a reliable setup Pokemon, so I made it a support Pokémon with rain dance. Air ballon is because damp rock is banned and I didn’t know what to use, but you can experiment with the item. You can also choose between thunder wave, toxic, or something else for the last slot, I’m not sure if your team needs speed that much. Volt switch is for a slow pivot that give you a safe switch for your sweeper.
Next, electric terrain. Obviously pincurchin is the only only electric terrain setter, so I made him defensive with spikes and rain dance again. Sucker punch is good for priority since it’s ridiculously slow, but zing zap is not as important. I feel like some sort of attacking move is important so you can hit setup sweepers, but it’s up to you. I replaced jolteon because you have a lot of special sweepers.
Now, if you’re having electric terrain, you should definitely have alolan raichu over the Kanto one. It’s a pretty basic set, it’s amazing in terrain but doesn’t need it. You can also use grass knot if you want.
Next, Rotom. Rain dance was a good idea for your team, but not on a specs Pokémon. I just tweaked it to make him more offensive. You can switch dark pulse for trick/another coverage move.
For galvantula, I thought that compound eyes loses its purpose since rain makes thunder auto-hit, so I switched it for heliolisk. It works really well in rain, weather ball is STAB for when it’s out of rain and ground coverage it it. Last move can be focus blast/grass knot/surf/protect for dry skin healing.
Finally, Luxray. Since you have to wait a turn to get burned, I’d give it agility over crunch to setup while waiting for the attack boost.
Those are my thoughts on your team. I hope I didn’t change too much and that my suggestions help!