Not only can you use the NFC figures, you can also use that smart card you have laying around in the game.
Pokémon Rumble U, known as Pokémon Scramble U in Japan, is going to make use of IC cards in Japan to unlock more content in the game.
These cards are typically used for making purchases, such as for train fare or for buying food and drinks from convenience stores or vending machines. The cards are can be pre-loaded with funds and then used by simply touching a special NFC reader. The game will allow players to scan the cards on the Wii U GamePad to bring assist Pokémon into the game. Scanning the card does not deduct any funds from the card.
It is unclear how many times the card can be used (i.e. how many times per day, hour, etc.) or if this feature will be included if and when this game comes overseas. Pokémon Rumble U launches on the Wii U eShop in Japan on April 24 for 1,800 yen ($18.33).