For this game, you will typically find two file types. While both run the same content, they function differently:
If you have obtained NSP or XCI files through legitimate means (like backups of your own games), here's a general guide: mario strikers battle league switch nsp xci u full
Mario Strikers: Battle League is a multiplayer-first game. The single-player "Cup Battles" are shallow (about 3 hours of content). Pirated copies cannot connect to Nintendo’s servers. You will be stuck playing against a mediocre AI, missing the entire point of the Hyper Strike mechanic and chaotic 4v4 online leagues. For this game, you will typically find two file types