Microgame sets on 3ds models
If you press the power button on any of the 3ds models in the toy room, a set of 3 micro games will start. What microgames are shuffled depends on which model of 3ds was turned on.
Wario Kard and Shuffler Machines
Turns out those character cards you get do something after all! Upon unlocking all items in the Arcade's Toy Room (in all categories), you will unlock Wario Kard on the Arcade menu. It is a special card game that allows you to use the cards you collected to beat opponents and earn more coins. The Capsule machine used will also disappear, being replaced with two "Shuffler" machines. These will dispense random character cards, including "B" and "A" rank versions of cards in your collection.
Arcade...