Disclaimer: I kind of hate art because my skillset revolves around code, story, system design and other such "behind the scenes" elements. I can "sort of" create art, but it's mostly just things like recoloring existing stuff. Character artwork takes me literally days and it's generally pretty low quality.
That said, I threw in my vote for "battle and event animations," but to clarify, I'm referring to event creation with existing assets to illustrate a scene, or cobbling together (hopefully) interesting skill animations using Yanfly's super-awesome and under-appreciated action sequence system.