Giga: Yes.
A Spinner is something that uses Rapid Spin to get rid of Spikes. Once they are out of the way, and you have Spikes down, there's no need for Glalie.
Choice Band doesn't make you use the first move in your set, it means after you use one move, you have to continue using that same move until you switch out.
Rain Dance increases Ludicolo's speed, in this case so it can outspeed the base 130's (Jolteon, Aero, Crobat, Mewtwo etc) and boosts Hydro Pumps power to 240 base (Ludicolo's water type as well), but it doesn't make it's accuracy 100%.