The Ferrum League acts as the story mode for Pokkén Tournament. It is separated into 4 divisions, Green, Blue, Red and Chroma. In this mode, the player must fight there way up to the top 8, after they reach the top 8, they must reach rank 1 in this mini tournament and from there, must pass the Promotion Test, if they do, they're rank will increase and they will be granted permission to enter the next league
As the player moves up the Ferrum League they will encounter Shadow Mewtwo, a dark, corrupted version of Mewtwo and a mysterious girl. As the story goes on, the player will the learn the identity of the mysterious girl: Anne. Anne informs the player that Mewtwo had been corrupted by the Dark Synergy Stone, in a effort to save Anne. Anne needs the help of the player to release Mewtwo from his corruption. After traveling through the unknown areas of Ferrum and passing some test, the player confronts Shadow Mewtwo for the last time. The player eventually wins the battle and frees Mewtwo. After the player frees Mewtwo, the player takes on the Chroma League and eventually wins, becoming the Champion of Ferrum.