Pokemon Rumble Blast. Simple, but really fun to play with a good deal of replay value.
Not going to hype it up, though; it's pretty much just a simple kids' game that I greatly enjoy playing and that has lots of replay value due to some of the systems they put in place that apparently weren't in the Wii game. While the game gets mildly "difficult" later on, most of the time you just have to grind some new toys or give your toys new moves. I do love it, but this game's definitely not an award-winner. : P