>>102113649
It's going to depend on which uma you're using but pretty much every horse who wants to run medium or long wants a minimum of 600+ stamina before URA.
Just bum a max limit broken super creek and 9 star stamina spark off some whale, and you're good to go.
Club > Club Menu > Rankings and then just look around the top 100, and you'll see a bunch of trainers who have crazy built umas you can borrow for legacy or supports.