So I was thinking, why not when a new building/shop is released a competition is held for who gets to be in the npc. Like, do a day long pk battle, or who can get the most robot spar wins in a day, or maybe host an event. Why should random people/staff get all the npc's? Make it a prize!
Ok, hold a hns event, a trivia event, a risk event, a race, a guessing game, rambo, first person to 50 streak, anything. Just make it a fun competition