According to the information from Steam and PlayStation Store, it seems like Dragon Ball: Sparking Zero might not have local multiplayer.
Dragon Ball Sparking Zero roster – every confirmed character
Dragon Ball Sparking Zero has no multiplayer. #greenscreen #anime #fyp
Dragonball Sparking Zero No Local Multiplayer Confirmed By Steam Will It Be Added Later?
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Dragon Ball Sparking Zero : NEW LOCAL MULTIPLAYER SPILTSCREEN UPDATE (GT Characters/Release Date)
The roster so far in DRAGON BALL: Sparking! ZERO : r/dbz
Dragon Ball: Sparking Zero Does Not Feature Local Multiplayer - Gameranx
Pretty massive update on DB Sparking Zero : r/Dragonballsuper