The Naruto Destination Tournaments Addon!

Runs full tournaments with automatic bracket generation, arena management and fight management
Admins register arenas and rules, players queue up during registration, and matches fire one after another with PREP / FIGHT / RESOLVE phases handled for you
Fighters are released into the arena when the match starts and PvP is auto-gated between them during prep and pauses
Prize pool with 5 tiers (1st / 2nd / 3rd / Losers Bracket Winner / Consolation)
Full bracket GUI with click-to-edit matches, admin panel, rules editor, history viewer, prize editor and personal rewards box
Admins can force-confirm wins, order rematches, or pick a winner directly from the match editor
Arena enforcer keeps fighters inside the arena boundaries
Fully Configurable

/tournament - narutodestinationtournaments.command.CommandTournament
/tournament create - narutodestinationtournaments.command.sub.SubCreate
/tournament start - narutodestinationtournaments.command.sub.SubStart
/tournament register - narutodestinationtournaments.command.sub.SubRegister
/tournament bracket - narutodestinationtournaments.command.sub.SubBracket
/tournament prizes - narutodestinationtournaments.command.sub.SubPrizes
/tournament rewards - narutodestinationtournaments.command.sub.SubRewards
/tournament history - narutodestinationtournaments.command.sub.SubHistory

This is an addon for the Naruto Destination mod and is entirely server-sided so no need to include it in your players' modpacks!