I am in a similar situation, my wife has limited cerebral palsy that results in diminished control of her left side. So while she does have a hand that can hold the controller, she does not have the dexterity to meaningfully do much with it. She could, for instance, play boxing.
I just noticed that Mercury : Meltdown Revolution is entirely done by the remote. So that's one for the list.
Be careful as well with the various games where it may say remote only, but what that means is "turn the remote sideways and work the buttons on both ends of the remote rapidly." At best, somebody in our situation might be able to hold the remote in one hand while working the buttons with the other, but rapidly switching between both ends of the remote (as opposed to using thumbs as a regular two handed gamer would) is not really a good way to play. In general, one-handed remote operation needs to be something involving swinging (such as tennis or other physical games), or pointing and shooting. Not so much with the traditional console / arrow pad controls.
Duane
Duane's Brain