According to a notice on the Nintendo Japan website (translated by Kyle McLain), save states and a Virtual Console menu will be added to Brain Training via a future update.
In January, President Satoru Iwata revealed Nintendo's plans to bring DS titles to the Wii U GamePad through its Virtual Console service to bolster the system's Virtual Console lineup. While Iwata didn't specify which DS titles would be introduced to the Wii U nor when, Nintendo illustrated in a presentation slide at the time how Brain Age might appear on the GamePad's screen.
"We are now sure that we can solve the technical problem of displaying Virtual Console software from Nintendo DS on the GamePad," Iwata said during the management meeting in January. "The dual-screen Nintendo DS, one of which is a touch screen, has a very strong software lineup, and so we plan to add the Virtual Console titles from Nintendo DS software to the future Virtual Console lineup for Wii U."
The upcoming releases are part of Nintendo's plans to prioritize the Wii U GamePad and make software that takes advantage of its specific hardware features. We have reached out to Nintendo about DS title releases for the Wii U Virtual Console in other markets.