Mega Man was announced to be coming to mobile devices late December 2016 but it is out now for Android devices. This extends across the entire NES series, ranging from MM1 through MM6. Reports indicate that the ports aren’t the best, having frame rate issues and control problems. But these are likely to be fixes through updates in the future.
Mobile ports of classic games need lots of work in feeling ‘right’ on touch screen devices. I could see the classic Mega Man games working but you need to do more than just having virtual controls and difficulty options. Either way, if you want to pick up these games for your phone, you can find it at the following link.