For RPG's I'd say:
Final Fantasy Tactics A2 - aka srpg made for the little crowd, Has some decent customization for individual units, around 300 quests in total and it is relatively simple as far as srpg's go.
Bowser's Inside Story - Nothing speaks Crowd pleasing RPG than the Mario&Luigi RPG series. The Reflex mixed turn-based battle system is a breath of fresh air with minigames thrown in for diversions.
Custom Robo Arena - Story is a 40 hour crap-fest, but the Real timed battles and robot customizations themselves more than make up for it. Think of it as a low budget Medabot anime series.
If I were you, I'd be playing the Kirby games since they Fit your description. I'd recommend Super Stars Ultra which is the best of the bunch.


, if you know some DS games that have a good replayability... a lot of game modes, smart and challenging AIs, something that even if finishing the campaign/story mode, there are still lot of things to do....i;m actually eyeing for metroid prime hunters, i enjoyed kid icarus 3DS so much, so i'm thinking if i may also enjoy playing the metroid prime hunters....