I would suggest replacing Weavile.
Why? Because anything Weavile can do, Greninja can do better (Ice Shard/Ice Beam, Night Slash/Dark Pulse, etc.). This means that you are also not sacrificing as much speed, as Galvantula and Weavile are both relatively speedy. This also lets you have valuable Electric support to take out bulky Waters, who this team has a small disadvantage against. I hope this helps!