I, frankly, hate Whimsicott; you can imagine what I think about Cottonee.
In any case, if a niche does not develop with Gothitelle or Gothitelle is removed at any point, it should be deleted / not reinstated. It is the sole holder of priority Memento, meaning that leading with it will make an unprepared opponent be at a huge disadvantage against an incoming SubCM Gothitelle (Jumpluff loses to Cinccino I guess). Outside of this, it is functionally useless, stopped by any Grass-type that exists.
I'm very happy to see that we have a thread like this.
VGC Regionals: VGC11 Top 16, VGC12 12th Place