Pros: Solid puzzle game, bright colors.
Cons: If you hate pokemon...
The bottom line: It's the SNES's Tetris attack, just with a Pokemon flavor. And Tetris attack was great.
If you've ever played the Super Nintendo game Tetris Attack, then you know everything there is to know about Pokemon Puzzle League. They took the old game, which had Yoshi and friends as its mascots, and slapped Pokemon pictures and sound effects onto it. Other than that, it's the exact same game, and it's good.

It's a simple tile-based puzzle game where you clear lines before it reaches the top, not unlike tetris. The difference is that the tiles don't have to be fitted together in any way, since they're already stacked in neat rows. What you have to do is sort them. There are several different kinds of tiles (the number of different kinds depends on the difficulty setting) and if you manage to line up three of the same kind then they disappear.

It sounds easy, and it is...if you're doing it by yourself. But you're not. The computer has a similiar grid right next to yours, and it's a race to make the computer hit the top before you do by instigating COMBOS, which are when you manage to eliminate more than three tiles with one move. (Clearing three tiles so that another falls into place and clears three more, etc.) The computer moves quite fast, so you have to as well. It gets quite frantic, but in a good way. It's quite addictive.