B.H.
Depends on how many folks are going to play. You need one for each person if you are playing a game where everyone plays at the same time. Even for games where you take turns (like the bowling or tennis). We have other games, like Mario Racing, where you race all at the same time. We have three kids and bought 4 controllers as we have a neighborhood child who comes over a lot. My daughter has a friend who brings her controller along when she comes to stay the night. Don't know about games for the little ones as my youngest just turned 15 - yikes.