I can tell you what the kids at the day care where I work are playing. I work with 5-year-olds as well as 6-10-year-olds in a separate classroom, both boys and girls. It may not be fully applicable, however, because they (the older ones especially) tend to focus on multiplayer games that they can play with only one cart via the download feature. There's a lot of New Super Mario Bros, Mario Kart, and Mario Party. Occasionally some other racing games come and go. The girls will sometimes play games of the "My ***" line or "Imagine ***" but it's hard for me to differentiate games in a genre for which I have no interest. The girls will generally play New Super Mario Bros. in multiplayer mode. Pokemon is always popular, though it tends to be the boys playing them. Also, it's worth noting that the only GBA games anyone ever plays these days are Pokemon.
The Kindergartners (without any discernible gender divide at all) generally play single-player games that everyone else looks over the shoulder to watch until their turn comes up. The Lego games (Batman, Indiana Jones, Star Wars) are popular as well as cartoon and film inspired titles like Ben-10 and Shrek. Mario and Sonic at the Olympic games was huge with last year's class -- they'd always report to me what place my favorite computer-controlled characters ended up taking. Other Mario games remain accessible. Pokemon is popular, but most of the 5-year-olds can't advance the story without help. Still, once they are able to do so, they seem very content to battle and catch wild Pokemon and play with the Pokewalker accessory even if they never challenge a gym leader.
I don't know how much help this will be overall, but I can say that New Super Mario Bros. is universally enjoyable. Other choices will depend largely on her interests and whether she will be joining friends in playing games together.
EDIT: Kirby! I forgot that Kirby is kind of the Kindergarten "ooh can I play that?" game of the moment.
) but if you know any of those that would be good to
