TL;DR on what the 120 star relay is for those of you who don't know!
There are teams of players who each select a segment of a 120 star run in which they will do! For example player 1 will do the entirety of Lobby (Whomps Fortress, Jolly roger bay etc) then when their segment ends another player picks up from where that player stops and does the next part until all players have completed their segments finishing at of course bowser in the sky after defeating bowser and collecting the star.