The first wave of Nintendo smartphone games being developed with DeNA will be free-to-play titles.
Earlier in the year, we learned a bit about Nintendo's foray into smartphone gaming, with the announcement of it's first app: Miitomo. Miitomo was announced as a free-to-play title, and we were told that other Nintendo smartphone games would be pay-to-download efforts. However, now The Wall Street Journal is reporting that at least the first wave of Nintendo smartphone games will all be free-to-play with microtransactions.
Nintendo plans to release five smartphone games by March, 2017, with Miitomo leading the charge this coming March. It is assumed that these initial five games are the "first wave" that is being developed in conjunction with smartphone gaming giant DeNA, and will all be free-to-play.
Nintendo did state in its reveal of Miitomo that future titles would be pay-to-download, but it looks like it will be a ways off before we start getting full games on smartphones.
It has also stated that it plans on building in cross-platform functionality with its smartphone apps and its hardware (the Wii U and the 3DS), as the primary purpose of these apps is to drive more users to buy Nintendo consoles.
Source: Wall Street Journal