The National Sluggers League, NSL, is an 8-man Mario Super Sluggers league in the central United States. The season runs throughout March. Each year, a series of offseason events take place. Joe is the reigning champion after the 2025 season, going back-to-back. Andrew is also a two-time league champion. He also won the first Mario Sluggers Online Tournament. The National Sluggers League takes pride in being the loudest, hypest, and best Mario Sluggers League on the Internet. 

The National Sluggers League is running its fifth season right now. The league has completed one week and three games per each team. The season has been the most successful in terms of live viewers.

Carston is back for the 2026 NSL Season. Carston played in 2022 and 2023 and put together an 8-11 record during his time in the league. He also played in the 2022 Fall Classic. He will be replacing Hayden and will reclaim his spot in the Night Division, which he was in during the 2023 season. He won his first two games of 2026 before dropping one to Joe.