Episodes of the Pocket Monsters anime which occasionally aired instead of a rerun from the main anime series as part of the Weekly Pokémon Broadcasting Station in Japan. They aired concurrently with Pocket Monsters Advanced from December 3, 2002 to September 28, 2004 in Japan. Outside of Japan, these episodes were only dubbed in the West as part of Pokémon Chronicles. 
(Source: Bulbapedia) 
Note: The Japanese version comprised 16 episodes while the U.S. version comprised 22 episodes; this page represents the Japanese version. The 6 additional episodes in the U.S. version were taken from previous movies and specials. Episodes 1, 2, and 3 are from Pokémon: The Legend of Thunder!, Episodes 4 and 20 are from Pokémon: Pikachu's Winter Vacation (2001), and Episode 22 is from Pokémon: Pikachu's Winter Vacation