What the crowd is shouting
The word is yoisho, not “yoshi.” It is a common Japanese exclamation used when making an effort or timing a shared action. “Heave-ho” is a useful English comparison, although there is no single exact translation.
During a Yokozuna dohyo-iri, spectators often call “yoisho!” as the Yokozuna brings a raised foot down in a ceremonial shiko stomp. The shout follows the movement and gives the ceremony a call-and-response rhythm. It is encouragement and participation, not an instruction to the Yokozuna.
The stomp itself has ritual meaning. The Japan Sumo Association explains it as symbolically driving evil from the dohyo. The crowd call is a familiar custom around that moment rather than a formal rule of the ceremony.