Moveable chords have no open positions. Blues guitar playing uses moveable chord forms as much as any other type of guitar style, including the common 6th-string root chords shown here:
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Moveable chords with the root on the 6th string.
Common moveable chords rooted on the 5th string include these:
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Moveable chords with the root on the 5th string.
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Some more complex moveable 5th-string-root chords.