Invitational
An invitational is a tournament that features an intentionally limited number of entrants. The players in an invitational are intentionally chosen by the tournament organizers, typically decided via direct invitation, a community-based vote, or by players qualifying through other events. As this tournament format cannot rely on entry fees from a large number of players to form the prize pool, a private sponsor or community donations are sought out to offset the deficit. The purpose of an invitational is mainly to showcase the highest level of competitive play in a condensed time period, essentially trimming the "fat" that pools and semi-finals introduce, which incidentally saves on budget that would have gone into renting a large venue for a long period of time.
While invitationals for the Super Smash Bros. series are fairly few and far between compared to more open tournament formats, some have obtained notoriety in the competitive scene. The largest scale invitationals has belonged to the Smash Summit, as well as Nintendo themselves hosting the Super Smash Bros. Invitational and the Super Smash Bros. Invitational 2018 for Super Smash Bros. 4 and Super Smash Bros. Ultimate respectively.