If 'Mario & Luigi: Bowser's Inside Story' wasn't included in the Mario games you gave to her, then put that in there. If the only indication of her gaming preferences are that she likes Mario, that'd be a better introduction to RPGs than something pretty hardcore like Pokemon.

If she has any interest at all in fashion, Style Savvy would be my next strongest recommendation. Aside from that game, I'd avoid buying *any* game for her just because it has a girl on the cover. I did not like 'My World My Way'.

Next on my 'general recommendations' tier are Rhythm Heaven and Elite Beat Agents, which I would include on any list of 'Games Every DS Owner Should Have (If They Can't Import Games)'.