Topic: Good Game controller for senior citizen?

There is a recent study from University of California, Irvine that says playing playing "Nientendo Super Mario 3D World" can help with memory. Super Mario 3D World game works for memory improvement where "Angry Birds" did not help. I have an elderly relative that has memory problems. I want to see if playing "Super Mario 3D World" will help.

What do I need besides the game Wii U for her to play this? I assume I need a Controller? What would be a good Controller for a senior? Something with big easy to use buttons would be best IMO. Is the Nintendo 3DS XL a viable alternative to the Wii U for this type of thing (especially since it is more portable)? Any other information would be helpful. Thank You! It is for a good cause and I will report back my results.
(Please excuse my ignorance. Although I am very computer savvy, I know almost nothing about Video games.)

The Wii U has a controller in the package, called the Gamepad. The Wii U, the game and a TV set to connect to (with HDMI) are all you need.

@jariw: Thank You. Since this is HDMI, will a LED computer monitor with HDMI work as well as a TV set or does it introduce new of problems?

@kinkajou I use a LED computer monitor connected using a HDMI cable when I play on my Wii U. The only problem I can imagine is the sound. A lot of computer monitors don't play sound. My monitor has an audio jack, so I've plugged some external speakers into it.