What is needed-
Wiimotes + Nunchuks + Motion plus (one lot for each player)
Rechargeable battery's lots of them.
This thread will help you in that
Classic controller. Only really needed for a handful of games and all the Virtual Console games.
Not needed just a waste of money.
Packs with add-ons for the Wiimote. They usually have a tennis racket, baseball bat. They just get in the way and are not needed