A unique attack that varies in effect depending on the Pokémon using it.
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All Nesubian Unown forms
The full set of (known) Nesubian Unown forms. Their appearances are based on Ancient Egyptian hieroglyphs—specifically the 'uniliteral' set of glyphs, which is very loosely similar to an 'alphabet' and also only has around 25 characters instead of hundreds. You can compare to the real uniliteral hieroglyphs here. (The 'lion' glyph shown there isn't actually commonly used according to my sources.)
Unown (Johto)
While the Nesubian Unown forms are by far the most common in the region, every once in a while Unown that take the forms of characters from other languages will appear...