If you already have the base P4AU NSP installed, grabbing the latest update is worth it for the network fixes alone. Just be careful where you source the update file—look for clean dumps with verified hashes to avoid corruption.
The Nintendo Switch version of Persona 4 Arena Ultimax (released March 17, 2022) is the most comprehensive version of the game, including all previously released DLC and content from the original Japanese arcade 2.5 update. Core Content Included Complete Story Collection : Features the entire original Persona 4 Arena story mode alongside the sequel story. Full Roster : Includes 22 fighters with characters from , plus their "Shadow" versions. Episode "Adachi" Persona 4 Arena Ultimax Switch NSP UPDATE
: Play as Adachi, Marie, and Margaret without extra purchases. If you already have the base P4AU NSP