Pros: Tons of PokéGoodies!
Cons: No Team Rocket or Kanto gym battles and no Meowth!
The bottom line: If you're too lazy to buy the cartridge, get an emulator and the ROM and join the fun. And for all those Pokémon haters: You're REALLY missing out big time!
I only played the ROM version of this. Sure, ROMs these days don't have good quality like the original. Most of the graphics were a bit scrambled up, so I could hardly tell what was what. (I got a better emulator called REW and the graphics are so much better.) But the game was fun nonetheless. Even though my feelings toward Nintendo were so-so, I jumped right into the Pokémon craze and may I say I'm proud of it.

I don't think there's a story, so I'll skip that part and head to info. There are several blocks with different shapes: hearts, triangles, squares, stars, exclamation points (challenge mode only), upside down triangles (not in challenge), and diamonds. You need to get 3 or more vertically or horizontally. Chains and combos really boost up your score (and they help a LOT in Challenge mode). Here's a list of the modes I've experienced:

Marathon: Keep playing till your stack reaches the top.
Challenge: Battle the Johto Gym Leaders, the Elite Four (Normal/Hard/Super Hard/Intense), and Lance (Hard/Super Hard/Intense)
Stages: Clear all blocks on top of the line
Puzzle: You have a certain number of moves and some panels you need to get rid of
Time: Get a high score in a certain amount of time
Garbage: Same as marathon, but "garbage" will be falling

I don't know anything about the two-player mode.

Next, my opinions.

GRAPHICS: 10
All the Pokémon looked the same as they did on Gold/Silver/Crystal. There were a lot of colors and basically were pleasing to the eye.

SOUND: 10
The music's great! I usually go to the sound test and listen to the music before I start playing. I could easily tell that there were a lot of remixed tunes from Gold/Silver and Red/Blue.

GAMEPLAY: 10
This game was easy to get into. At first I was pretty confused, but now I'm unbeatable...almost. My favorite mode was Challenge because it's really fun.

REPLAY VALUE: 9.9
You'll be stuck with it. ROM or cartridge, you be playing for hours. It's enough to put your fingers to the max!

OVERALL: 10
An awesome game. I just wish they put Meowth somewhere in the game. (I'm a big Meowth fan!) I was also surprised that you don't get to battle Team Rocket or the Kanto Gym Leaders. But then again I never expect too much from puzzle games.