Is there anything the Poke-critters can't do? As much as you want to write them off, the sickeningly-adorable little monsters manage to sneak into a decent game from time to time. In this case, it's a falling-blocks puzzler called Pokemon Trozei.
Instead of blocks tumbling from the sky, it's a bunch of Pokemon. The bit is to line up four of the same type horizontally or vertically with the stylus. Once you do - pop, they disappear like Tetris blocks. After you match four, you only need three to make them clear. Then just two. At that point you can really start cleaning the board. The catch (of course there's a catch) is you have about two seconds to keep the combo going before everything resets. If you're not fast enough, you gotta start all over again by lining up rows or columns of four.
So that's the gist of Trozei. What makes it a little deeper and more rewarding than other puzzle games of this ilk are the various collecting bits. Every time you clear (or trozei) a group of Pokemon, that creature is added to your captured Pokemon list. Some of the little guys are harder to find than others and only appear if you're clearing some serious lines. It's not much, but just by adding a goal to the normally-endless puzzle game, you get a few extra miles of gaming.
Then there's story mode, in which you follow some Powerpuff Girls knock-off around as she reclaims a load of stolen Pokemon. The best thing here are the versus matches against evil Poke-wranglers. They can throw blocks in your puzzle set that can only be cleared in the middle of a larger trozei - the bad guys, too, have to be hit with successive trozeis to be beaten.
Trozei offers single- and multi-card two-player games of the versus and co-op variety. Every player can also fill out an Agent Card that transmits out to other DS owners (think Nintendogs' Bark Mode), but other than telling you how old the other person is, the card isn't much use. Who cares, right? Trozei's got plenty of still-solving-it-in-your-dreams gameplay to last for a long time.