characters with sentient outfits has the chance to go berserk
Then by that logic all Fate characters with dark "Alter" fan designs must be tagged spoilers as well. And all fan made designs of any Mega Pokemons. And all the images of any 'alternate universe' scenarios. And all pair shipping images of characters who doesn't get together in canon. The list goes on.
Fanon ideas with possibilities of becoming real in canon doesn't constitute for spoilers, which is supposed to be for something that should have already happened in canon proper.
This is such weird and unexpected gif (I would think these two would be trying to kill each other while in their berserker modes) but I can't stop laughing at it.