Nintendo - Pokémon Puzzle Challenge

Provides a description of the game including screenshots.
http://www.nintendo.com/gamemini?gameid=m-Game-0000-294

Game Winners

Contains cheats and codes for the game.
http://www.gamewinners.com/game_boy_color/PokemonPuzzleLeague.htm

GameFAQs

Provides cheats and codes including unlockable characters.
http://www.gamefaqs.com/portable/gbcolor/code/27856.html

GameSpot

Reviewed by Frank Provo. Includes screen shots, cheats, hints, and reader ratings. Score: 8.9 out of 10.
http://www.gamespot.com/gbc/puzzle/pokemonpuzzlechallenge/

eLook - Pokemon Puzzle Challenge

Quick summary of cheats and codes
http://www.elook.org/games/cheats/gbc/620.shtml

GamePro

Offers information and a review.
http://www.gamepro.com/nintendo/gameboy_color/3664/info.shtml