The main trick is to have a sport that no-one else plays then running a "world series" or "world championship" that no other country is eligible to enter
But it doesn't always work. The City of Lancaster has, for the past five or six years, held the International Sedan Chair Championship races. Typically, there have been six or eight local teams as the only entrants. Last year, a team from Denmark competed. They did well, although they didn't win. But with this experience, they will return next year and win - you can bet your breeches on it!