i saw your question on the villager trading/buying thread so i figured i could answer :~ ) when a villager wants to move, on their last day (when their house is packed into boxes), someone can come to your town and talk to the villager. if they have space or haven't already had the villager recently, the villager will offer to move to their town. if they say yes, the villager will show up in two days. people often pay bells/items to have the right to ask the villager to move into their town. vice versa if you're the buyer, and not the seller. hope this helped you a little.
