From Bulbapedia, the community-driven Pokémon encyclopedia.
The web site of the programming block Kids' WB! had several Pokémon-related online games.
Pokématch is one of Kids' WB!'s Pokémon games. The game features a 6x6 grid of tiles featuring Poké Balls. Tiles are flipped to uncover Pokémon. Each Pokémon must be matched with its evolved form, and in doing so, removes the tiles from the grid. Removing all the tiles uncovers a picture.
Pokématch was released in 1999.
Not so much a game as a poll, but included in the games section, Smell-O-Meter allowed users to vote for whichever Kids' WB! character they thought had the smelliest sock. One of the choices was Jessie.
Pokémon Puzzle Challenge: Online Challenge
This game was not actually hosted on the Kids' WB! site, but the games section included a link to it on the Pokémon Puzzle Challenge site. The game gave the name of a Pokémon, and the player had to click on that Pokémon's picture before time ran out. There are three levels.
Kids' WB! Turkey Day Food Fling
A Thanksgiving-themed game where characters from various Kids' WB! shows would pop out from behind crates at the foot of the water tower, and the player has to throw food slop at them. Hitting bad guys awards points, but hitting good guys takes points away. Pichu is one of the good guys, and is also featured on the title screen.
Mesa Bumping Madness
A game where two characters battle in bumper cars. Within a three minute time limit, players must bump each other out of the ring. After being bumped out three times, a player loses. Crates containing bonus points also appear. Playable characters include Pichu and Ash.
Hip Hop & Bop!
In this game, the players controls a Pichu, who is hopping from cloud to cloud in an attempt to reach the top of the Kids' WB! water tower. Pichu must avoid flying Lugia (called "birds" in this game). The clouds constantly move from side to side, so timing is essential.