This index is about ball tropes — traits temporarily imposed on an arbitrary character for narrative purposes — "The Plot needed someone to be a Hero in this scene". While this does help move the plot forward, it runs the risk of feeling rather contrived.
Note that Timey-Wimey Ball does not fit this criteria and this does not count, despite the name. Nor does any tropes about actual spheres, like Happy Fun Ball, Energy Ball, Weaponized Ball, or Ball-Balancing Seal, although something being temporarily weaponized for the sake of the plot does happen. See Shapes and Symbols Tropes for those. If you're looking for the type of Ball that involves dancing, that's at Dances and Balls. These are often Tropes Hidden from Audience, as they're used for the convenience of the work's creator.
- Advantage Ball: At least temporarily, one side holds total advantage.
- Conflict Ball: Character(s) starts a sudden conflict for the sake of the plot.
- Distress Ball: Character is in a dire situation because they made a poor, easily-avoidable choice.
- Hero Ball: The hero, specifically, has a lapse in good judgement and makes a dumb decision.
- Idiot Ball: For plot purposes, a character suddenly becomes quite dumb.
- Jerkass Ball: Normally-nice character(s) suddenly becomes a jerk for the plot.
- Kindness Ball: Normally-mean character(s) suddenly becomes nice for the plot.
- Retroactive Idiot Ball: When a character seems to have suddenly become quite dumb because of a concept or element that was introduced into the universe after that particular installment was written.
- Sanity Ball: Characters take turns being the Only Sane Man.
- Smart Ball: A moment of great but uncharacteristic genius from a typically dumb character, for the plot.
- Snark Ball: When their stupidity isn't relevant, dumb characters become Deadpan Snarkers.
- Strawman Ball: To tackle a controversial subject, one or more characters hold the "right" opinion, while others get this and hold onto the "wrong" opinion, regardless of whether it seems fitting for them or not.
- Villain Ball: Villain(s) makes a stupid decision just to be more evil.