1. Localized arena's around a world in danger zones, where player's have to come if wanna particape in tournament,
2. Use curently arena's in every village for automatized event,
Kage or Jonin can host it for "X" amount of ryo and those points which villager's collect by doing mission's ("Sand village intel" etc.).
also make player which host able to change options like do 2vs2 or 1vs1, sand exclusive tournament or for every village etc..