The remainder of this article contains lore created collaboratively by the Blaseball community.
Hlorses are bipedal. Hlorses are Fast. Two horses cannot physically fit into a hlorse costume and attempt to gain entry to a blaseball game, so don't worry about it. Many league players are hlorses. Some players simply ride Hlorses, like Jaxon Buckley who rides his Hlorse Fl'thc'r around the bases
Hlorses are pack hunters and are capable of guttural vocalizations approximating human speech. An ancient compact was forged between hlorses and cowpokes, granting cowpokes the permission to ride hlorses, and in return granting hlorses the permission to play blaseball.