fighting windmills; tilting at windmills; one-sided struggle
Idiomatic expression for a futile, one-sided effort where the opponent is imaginary or unresponsive; often used with 取る (一人相撲を取る).
Nobody took his protest seriously; it was completely a one-man fight.
That politician always seems to be tilting at windmills.
solo sumo performance; one-man sumo show
Historical term for a street performance where a person mimics a sumo match alone, often for entertainment or begging.
In the Edo period, there were street performers who put on solo sumo shows.