The rewritten Style Guide has an open discussion of the spoiler policy. The current policy will be used if no new consensus is reached. Discuss it here.
✨
Usage:
{{NeedsEffect|<effect name>}}
where
{{NeedsEffect|Bike}}
will return ✨,
{{NeedsEffect|Stretch, Spring, Glasses|and}}
will return ✨ (note that and is optional, as that is the default value of the second argument),
{{NeedsEffect|Child, Fairy|or}}
will return ✨.