While improving on nearly every problem with the original, this sequel still leaves much to be desired.
The gameplay is beat 'em up at its purest. You can defeat wave after wave of enemy Pokemon by smashing the A and B buttons. There is some strategy, using moves of certain types to get an advantage over the enemies, but it's mostly whether or not your Pokemon is a high enough power level to overtake the enemies. There are a large variety of moves to use and they keep things fresh, as every type has multiple viable moves to use. The stages are largely improved, as instead of 6 stages repeated every world, the game is divided into many levels with 2-6 areas, each area unique in contents. Unlike the original, this game features a story. However, it is pretty shallow as the biggest part of the story doesn't affect anything, a huge missed opportunity. It's pretty much an excuse plot, but it's better than the feeling of nothing really progressing in the Wii version. The main game is easy, but it can be unbelievably hard in the postgame at points.
The graphics are very similar to the WiiWare version. The Pokemon appear as Toy Pokemon, which is drastically different than any other Pokemon in the main series. It is incredibly charming, but there are quite a few Pokemon who don't fit well with the style and look downright awkward. The backgrounds and textures are nothing special, but they work for the game. When the action heats up there are some frame rate issues, but it doesn't really matter unless you're in the middle of it. The music is bland. It's pretty much elevator music, but it will get stuck in your head. It's nice to hear remixed versions of the original music, however.
The biggest improvement is the inclusion of nearly every Pokemon in existence. The original had less that 250, and this game includes over 600. While it makes collecting quite a few of them huge chores, it really adds to the replay value.
Speaking of replay value, this game is interesting. After progressing through the main story, there's a lot more to do than the original, but it's all the same. Every part of this game is the same. If you're looking for varied gameplay, look elsewhere. While it's fun, smashing A through dungeons hundreds of times collecting money turns into a chore.
While this game improves on the WiiWare original in nearly everyway, it still has major issues. The music and graphics are nothing special and the gameplay is the definition of repetitive. Despite that, it's certainly fun and the style is incredibly cute.