Original: It was then awarded to the NHL playoff champion in 1925 â "26 and 1926 â" 27, (supplementing the O'Brien Cup) before that team would go on to face the Western Hockey League (WHL) champion for the Stanley Cup. After the demise of the WHL, however, the Stanley Cup was awarded exclusively to the NHL playoff champion, and the Wales Trophy was given to the regular season champion.
Simplified: It was first presented to the playoff champion of the NHL (replacing the O'Brien Trophy) who then went on to face the Western Hockey League (WHL) champion for the Stanley Cup.